Somehow the installed QV tasks got stopped and didnt restarted while trying to restart. Mainly QDS was not working whenever you try to start through Services. Then DSC and QVS failed too. (Probably the reason was there was some problem in Credentials through which they were installed). Earlier the BackUp XML files were available in QVPR folder.
Later on all the services were uninstalled, again fresh installation was done for all the 5 services with new credentials. and some new paths (SourceDocuments, UserDocuments, TEMP etc) were set up on QMC. So now only today's XML Files are available in Backup folder in QVPR. Rest all others are gone!!!