Microsoft's backup system can do the oddest things. The usual advice is to never use MSFT's backup software but let's talk about getting the drive back to full size.
Look for Windows 8 own drive management tool to look at the partitions and then partition as you desire. Let's hope this is not a question about date recovery.
Bob
Bought a new computer with Windows 8 (previous one was vista). I thought I was reasonably proficient with a computer, but Win 8 has me baffled so far. I was trying to do a system backup on a 1TB external hard drive and couldn't find the place to do it. Finally came across system restore. It said I would need at least 16mb. Well, obviously, no problem. But, what it did was reformat my drive to 32GB. Have I lost my 1 TB hard drive? HELP PLEASE!

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic