If you have vss(volume shadow copy service running you may get the files back). If you shutdown your database properly any time recently you can try to restore all database files on that date from Previous Versions and try to open. You can back up all files you have now in a different folder.
os:windows server 2008
delted in IT scan
No Anti Virus, No backup.
So it is not Production database? then lets check whether you can able to refresh from prod division.
If it is very critical as per your concerns, Submit an SR to Oracle Support.