Hi, i was have problem on my HDD so i was backup my files to a GZIP (tar.gz) and i was formated my dedicated and isntall again but now i can't open my tar.gz file, i think my tar.gz file have a problem, how can i repair my GZIP file ?

Error Log :

gunzip < backup.tar.gz | tar xvf -

gunzip: stdin: invalid compressed data--format violated
vhosts/
vhosts/.skel/
vhosts/.skel/0/
vhosts/.skel/0/cgi-bin/
vhosts/.skel/0/cgi-bin/test/
vhosts/.skel/0/cgi-bin/test/test.cgi
vhosts/.skel/0/httpsdocs/
vhosts/.skel/0/httpsdocs/img/
tar: Skipping to next header
tar: Read 2048 bytes from -
tar: Error exit delayed from previous errors