Need Help --- After reboot a sql server in ESX4.1, a new Delta file created but old one disappeared

We have a sql server installed on ESX4.1,  this is a retired server for old data retrieve.

This morning we found this server's SQL server not work, so we re-start it. after we restart, the data base back to 7 years ago. 

We checked log file attached with file name (vmware-62.log),  in 30th Sep. 10:53:17  the server shutdown and turn off the file with name: mov-test2-000003-delta.vmdk

In next log (vmware-63.log) , in 30th Sep. 10:53:55 the server start with mov-test2-00004.vmdk .

We did nothing but restart the SQL server in VM.

The old file mov-test2-000003-delta.vmdk and mov-test2-000003.vmdk are disappeared. 

Can any one help ?

Thanks