I was playing in a tournament yesterday and i was playing a backhand shot, and then I held my racquet to play the next shot, but my racquet looked like this: I was completely shocked. I thought it may have been a mishit, but the damage seems quite serious. I did restring the racquet a few days ago, so maybe that could have been the cause?
Wow, how much tension did you string it at? It looks like the frame collapsed to the pull of the mains strings at the corner due to a mishit. You're sure you didn't clash it with another racquet? Have you ever clashed it before you had it restrung the last time?
Possibilities are: Stringer did a really poor job. OR There was already a small crack, and the racquet was too weak to sustain the string's tension.
If this is (was) a 4U racket, then that wouldn't have helped matters either - the slightest knock to a light racket can "contaminate" it from that point on. I can't see it having been the stringer's fault, as it would have taken a real clown to damage a racket at 23 (but hey, what do I know - there could be some real cowboys out there). Strung at 23, though, you should be able to claim on the warranty, especially since there was no clash. You should definitely give it a go.