kenta wrote:I had a Windows partition not working, and a Mint partition working on my computer, when i decided to try repair the first one. I used the Windows CD and it repaired that partition (i can see it from GParted), but there comes another issue. My Mint partition is now Unallocated for Gparted. I tried the liveCD and the liveUSB (both Ubuntu and Mint), but it seems that my partition is no longer there. I would simply install the system another time, but it seems too strange for me to be true. The fact is, the partition was a primary partition with two secondary partitions (Mint and Swap), and while the swap is still there, the mint one is disappeared. I can't see why this is possible (and why windows could format another partition without touching it).
I agree with oobetimer; your best bet is to use TestDisk or some equivalent utility.
To address some of your confusion, though, Microsoft's partitioning tools are known to have bugs that can cause them to delete partitions. This is one of the reasons that many Linux users strongly recommend against using Microsoft's partitioning tools except when absolutely necessary. That said, if Windows wasn't booting, you had little choice but to use those tools. You were in one of those "absolutely necessary" situations and Microsoft's bugs bit you.