someone has deleted half of the oracle files off the server (but not the data files). As far as I can gather it is the actual Oracle program that has gone, as we still seem to have the dbf files and at least one control file...
As im a developer rather than a dba (until now), im at a bit of a loss....
Also it seems tha there are no backups ......(!). Is there any way I can reinstall Oracle and use the database files and control file to get everything back up and running....?
If you are able, get a consistent backup of some kind, either export or datafiles immediately.
If all your database files (.dbf, control files, online redo's (or archived redo's) are truly intact, you won't have to do any file restore. Just reinstall your exe's (be sure the ORACLE_SID is set to something other than your actual database SIDs). Apply any need patches. Check your alert.log to be sure what patch level you were running at.
Even if you had a crash shutdown, Oracle should start up fine when the exe's are back. If your online redo's are intact, it will perform crash recovery as usual. If there are files missing or corrupted, deal with it after the install.
Then go track down the perpetrator(s) with a pointy stick. (Just a little DBA humor there.)