Hi
First question, was the E drive on the same HD as the C drive, or was it created on a seperate HD if it was on the same drive read below
its possible that someone had previously used a partition manager to create the E drive, and as most system restores are written by the manufacturer of the PC and will return the HD back to its original condition that is with 1 partition, the C drive, because any user created partitions are removed during the restore then any information is now gone.
However if the E drive exists on an seperate HD then you have either a faulty drive or some other problem.
You could try a file restorer program, there are plenty available, some free, some limited demo's and some that cost money but are worth it.
Let us know
Regards