My DVD Rom is detected in BIOS and I can see that but in My Computer isn't available

Reboot your system, login, and immediately take a look at Control Panel -> Administrative Tools -> Event Viewer - see if something in the Application or System logs gives any clues.

Try reinstalling any burning software you have, such as Nero or Roxio. If you installed any other software with your drive, try reinstalling that as well.

A copy-protection (or other) filter driver may be been installed when you inserted and let autoplay a disc, and that driver may be malfunctioning. You may snag a copy of Sysinternals' Autoruns and look in the drivers section for any optical drive related drivers, and try disabling them.

If you have a Windows system restore point available at a point you know the drive worked properly, that may be an easy fix.

There's also a slight possibility that the drive may be actually recognized by Windows, but merely not assigned a drive letter. Control Panel -> Administrative Tools -> Disk Management (or Winkey + R -> diskmgmt.msc to check that).