windows won't load-says disk error

everytime I turn on it just says error reading disk & to press control-alt-delete to reload. When I do, it shuts down & comes back saying the same thing. What can I do to get Windows to load?

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 1
crwdns2934285:0crwdne2934285:0