Import Database from Oracle .DBF files Recently my Oracle Installation has been crashed and I reinstalled the Oracle again. I have my old Oracle Data files (.DBF files) which have been recovered from old installation.

Now, I need to restore or reinstate these .DBF files into my new installation, so that I can get all my data and procedures.

Both Old and New Oracle Installation version: Oracle 12c
According to your description, the specific answer depends upon what and how the original backup was done. If it was a cold backup of OS file copy after the database was cleanly shutdown then you can restore the database BUT make sure you also have control and redo log files copied together with the DBF files. First copy all the complete and correct files to the target system in the exacly same location as these were in the original database before. Make sure that the version of the database is same. Then you can simply open the database normally.

Here is a similar post regarding the issue that you have mentioned here.
Mounting a database from database files copied from a previous installation

Cold Clonning Using controlfile backup in oracle 11g