Whatever the case, don't give up! Errors are common occurrences. Tell yourself it's okay to have them. They make your item unique. Heck, at times you can even discover a stitch you've never made before.
When all else fails, find humor in your errors. This family made a film as proof of their mom's error...poor lady was aiming for a scarf with 35 stitches and ended up in the 200's! Can't you just imagine her being enthralled in a TV show and ending up with a sweater instead of a scarf?