If you check the alert log you will get message similar to
Recovery deleting file #7:'<Oracle_Home>/db/dbs/UNNAMED00007' from controlfile.
Now you have 2 option
1. If you have backup of that tablespace TS1 then you can restore and recover it
If you don't need that tablespace then you offline drop that datafile 7 . Open the database in resetlogs mode and then drop tablespace TS1