Uhh, seems that I forgot to put that in the post. I do have a restore point, actually two, but they are too actuall, they wont solve my problem. I used to have bigger ones but they just disappeared. I think it has something to do with the amount of space on the disc I save for the restore points.
The instructions on the error say that I should reboot my computer. I did that several times, didn't work.
About the picture here, I hope this will clarify everithing.
About what I was doing when the partition disappeared:I was messing with the format tools of my external hard drive. It has 1.5 TB and it was formatted in NTSF(something like that) and it needed to be formatted in WBFS. But for it to be formatted to WBFS it needed to be formatted in FAT. So I created a partition in the External Hard Drive and formatted it to FAT. But then oh-oh error, the blue screen of death and the PC crashed. I rebooted and everithing seemed to be fine, the External HDD was formatted in WBFS and everithing was working fine. Except that my D: drive was missing!