Stuck in bootloop and not rooted, How to back up data?

So, my phone is stuck in a bootloop. I can restore factory setting, but first i want to back up my data, specifically my text messages. They are very important. Is there a way i can do that ?

the bad news is Im not rooted. now im trying to find ways to save data from my the phone before i do a factory reset. i hope im lucky. maybe you guys know how to do it.

Thanks,
btw its an Htc desire S

anyone?