Hi Sapen

You need to get in touch with whoever looks after the storage system for that server.

The errors are from SQL Server trying to access tempDBs data and log files and it cant find the disks. Either the disks became detached from the server or the IO system had an error when it tried to access a page from the disks.

Either way get your SAN or Server guys to look into it ASAP. Once they have diagnosed and fixed the issue a restart will re-create tempdb. I'd recommend doing a checkdb of all other database if/when you get the server started again to make sure no other issues have occured.

Mat