Most apps on my iphone 3g won't open

Okay so yesterday i synced all the music from my computer to my iphone 3g. And i used facebook and whatsapp normally last night right after i synced. And now it blinks, as if it's going to open, or it starts a little, like facebook gives me that blue screen, and then it exits. Why why why! What can i do!

Reboot your phone

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