Thanks for replying fast!
shorena : in debug.log (it is called only "debug") the last messages are :
"2015-12-23 22:56:38 ERROR: CheckProofOfWork(): nBits below minimum work
2015-12-23 22:56:38 ERROR: ReadBlockFromDisk: Errors in block header at CBlockDiskPos(nFile=27, nPos=119786418)
2015-12-23 22:56:38 *** Failed to read block"
goldtiger69 : Yes,but I've already exchanged my 2 two files (wallet.dat,debug,blocks,chainstate,......). I know the location of this fles,I'm using Windows.
I've just retry to exchange the data (the old wallet.dat and the last),and it is the same... I can't open Bitcoin Core,after the loading of blocks.
Keep your backup safe, erase every directory of Bitcoin: the regular one and the hidden one; re-install Bitcoin core from zero.
If that doesn't work, then check the files that you are using to install Bitcoin; they might be corrupted or something.
And like Shorena said: just to have a hint, check the debug file, maybe there is something wrong on your system, like ports or something.
Hope that helps, and you're welcome.
PS: Btw, when you re-install Bitcoin core, ONLY replace wallet.dat, no other file.