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.