then try resetting PRAM:
. . .
I can't use time machine because it starts then stops and say that it is not possible.
What message are you getting? Is it "An error occurred while copying files to the backup volume"? If so, that's probably a damaged file. See #C3 in Time Machine - Troubleshooting. It will show you how to locate the message(s) that describe the problem, then help you fix it.
If that's not the message, see #C2 in the same link.
Guys thanks for your help !!
After a lot of work I managed, and learned a lot of thing on the way.
I used an external HDD and installed MAC OS on it from other MacBook, then I booted from my External HDD and installed DATA RESCUE 3 and TECHTOOLS 6 then did a couple of repairs and scan on my internal HDD, and finally a full HDD CLONE with DATA RESCUE 3 from my internal HDD to another external HDD.
And so saved everything I needed !!
Thanks for your help !!