sqlserver not able shoqing my user dbs and system dbs

hello..
  today morning one of my sqlserver after long read and write operations  happen to tht server, after few minutes i saw in the instance tht db showing recovery -pending mode... At the same time i checked sqlsderver log file also...
error detaisl is:
05/25/2011 10:07:10,spid15s,Unknown,Error: 5120<c/> Severity: 16<c/> State: 101. 05/25/2011 10:07:10,spid12s,Unknown,FCB::Open failed: Could not open file F:\SQLServer2005\Data\navioffer_Feb11.mdf for file number 1.  OS error: 2(The system cannot find the file specified.).
after this, i went for IT support team and i restarted the sqlsderver services , once it finished i logedd in instance now not able to seen even signal db ..in this instance
once again i went and i verified my sqlserver log and event log ...
sqlserver log:
      &n ...