aspire 5742z recovery cd

is there anywhere you can possibly download these? i picked up a aspire 5742z cheap because it would start loading and then blue screen would pop up with a bunch of stuff before it would just restart. i would preffer to try recovering the original operating system but can't seem to do it. i have tried doing check disk and it seems to have been fine. i have also tried the Alt F10 trick and that did nothing. any help would be greatly apreciated.