I had a contract for supplying manpower for 28 days for 28,000/-. However, after 10 days, the service has stopped. Should I raise an invoice?

Yes. Where a supply of service ceases before its completion, an invoice has to be issued at the time the supply ceases, i.e., on the 10th day. The invoice shall be issued to the extent of the service provided before its cessation. (Section 31(6) of the CGST Act,2017).

(ICAI FAQ PUBLICATION 06-09-2017 -: Tax Invoice, Credit and Debit Notes : FAQ NO. 12)