Is your SQL server virtualized?
Do you have your C: drive for the server on different volumes of your sql data drives?
Are you running SnapDrive and Snap Manager for SQL, if so what versions?
What version of Ontap are you running and what model of NetApp filer?
Which snap partition was mounted? The snap of C drive or the snap of one of your data luns?
There is not enough information in your post to accurately troubleshoot.