The Tennessee Code defines when an apartment is "abandoned":
Quote Quoting Tennessee Property Code, § 66-28-507. Absence, nonuse or abandonment by tenant.
(a) If the rental agreement requires the tenant to give notice to the landlord of an anticipated extended absence in excess of seven (7) days as required in § 66-28-404 and the tenant willfully fails to do so, the landlord may recover actual damages from the tenant.

(b) During any absence of the tenant in excess of seven (7) days, the landlord may enter the dwelling unit at times reasonably necessary.

(c) If the tenant abandons the dwelling unit, the landlord shall use reasonable efforts to rerent the dwelling unit at a fair rental. If the landlord rents the dwelling unit for a term beginning prior to the expiration of the rental agreement, the rental agreement is terminated as of the date of the new tenancy. If the tenancy is from month-to-month, or week-to-week, the term of the rental agreement for this purpose shall be deemed to be a month or a week, as the case may be.
Abandonment, and the landlord's associated duties, are further defined:
Quote Quoting Tennessee Property Code, § 66-28-405. Abandonment.
(a) The tenant's unexplained or extended absence from the premises for thirty (30) days or more without payment of rent as due shall be prima facie evidence of abandonment. The landlord is then expressly authorized to reenter and take possession of the premises.

(b) (1) The tenant's nonpayment of rent for fifteen (15) days past the rental due date, together with other reasonable factual circumstances indicating the tenant has permanently vacated the premises, including, but not limited to, the removal by the tenant of substantially all of the tenant's possessions and personal effects from the premises, or the tenant's voluntary termination of utility service to the premises, shall also be prima facie evidence of abandonment.

(2) In cases described in subdivision (b)(1), the landlord shall post notice at the rental premises and shall also send the notice to the tenant by regular mail, postage prepaid, at the rental premises address. The notice shall state that:

(A) The landlord has reason to believe that the tenant has abandoned the premises;

(B) The landlord intends to reenter and take possession of the premises, unless the tenant contacts the landlord within ten (10) days of the posting and mailing of the notice;

(C) If the tenant does not contact the landlord within the ten-day period, the landlord intends to remove any and all possessions and personal effects remaining in or on the premises and to rerent the dwelling unit; and

(D) If the tenant does not reclaim the possessions and personal effects within thirty (30) days of the landlord taking possession of the possessions and personal effects, the landlord intends to dispose of the tenant's possessions and personal effects as provided for in subsection (c).

(3) The notice shall also include a telephone number and a mailing address at which the landlord may be contacted.

(4) If the tenant fails to contact the landlord within ten (10) days of the posting and mailing of the notice, the landlord may reenter and take possession of the premises. If the tenant contacts the landlord within ten (10) days of the posting and mailing of the notice and indicates the tenant's intention to remain in possession of the rental premises, the landlord shall comply with the provisions of this chapter relative to termination of tenancy and recovery of possession of the premises through judicial process.

(c) When proceeding under either subsection (a) or (b), the landlord shall remove the tenant's possessions and personal effects from the premises and store the personal possessions and personal effects for not less than thirty (30) days. The tenant may reclaim the possessions and personal effects from the landlord within the thirty-day period. If the tenant does not reclaim the possessions and personal effects within the thirty-day period, the landlord may sell or otherwise dispose of the tenant's possessions and personal effects and apply the proceeds of the sale to the unpaid rents, damages, storage fees, sale costs and attorney's fees. Any balances are to be held by the landlord for a period of six (6) months after the sale.
Assuming the landlord is purporting that there was some form of default by the tenant, any associated right to terminate is waived by subsequent acceptance of rent:
Quote Quoting Tennessee Property Code, § 66-28-508. Waiver of landlord's right to terminate.
If the landlord accepts rent without reservation and with knowledge of a tenant default, the landlord by such acceptance condones the default and thereby waives such landlord's right and is estopped from terminating the rental agreement as to that breach.
For unlawful eviction:
Quote Quoting Tennessee Property Code, § 66-28-504. Unlawful ouster, exclusion, or diminution of service.
If the landlord unlawfully removes or excludes the tenant from the premises or willfully diminishes services to the tenant by interrupting essential services as provided in the rental agreement to the tenant, the tenant may recover possession or terminate the rental agreement and, in either case, recover actual damages sustained by the tenant, and punitive damages when appropriate, plus a reasonable attorney's fee. If the rental agreement is terminated under this section, the landlord shall return all prepaid rent and security deposits.