Backed up with 3 disks, Restore asking for a 4th disk

Hello, I'm really hoping someone can help me, last year I backed up my pc (windows7) and it used 3 disks to back up.... I'm trying to restore from that back up because I'm in need of tax docs that are on that back up... Now, during restore I get a message stating to insert disk 4....There was never a disk 4 because the back up only used 3.... What can I do to retrieve the files off of my back up disk because it automatically cancels the restore when disk 4 isn't available. Please help.
Sincerely,
HBDean

Actually it is not the disk 4.

Just insert the disk 1 will end the process.

Disk 1 is required to complete this process.


Disk 1 is to start the process, and also to end the process.

A bit misleading.