Quote from: Ziat on December 23, 2015, 11:20:31 PM

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.

As GoldTiger69 said delete all files in the folders blocks and chainstate you will need to redownload bitcoin core.

Alternativly you can try to just delete file 27 (so blk00027.dat and rev00027.dat in blocks), but IIRC it does not help.

You might also want to check if you have anti virus software running that might cause the issue. You should exclude the blocks and chainstate folder as someone uploaded virus signatures into the blockchain a while back.

Finally it might be a sign that your disk is failing.