[Grml] save important data with grml

Hi! I wanted to Install Windows on a computer where debian was already installed. after istalling (no error messages), I didn't see any boot manager, just "NTLDR is missing"* I installed windows again. I saw my partitions, but then the same error happened again. I tried to install debian. I didn't see my partitions(!) I ran knoppix 4.0.2 DVD and grml 0.8. I saw my partitions, but they seemed to be emty. (how) can I save my important data?

*two notes:

1# the error "NTLDR is missing" is my personal translation of "NTLDR fehlt(german)" maybe this tanslation is not correct.

2# when I ran "cfdisk" on grml when it worked, it crashed with a error I don't rember... I think it was "irregular size" or anything like that.

greethings johannes