Jailbroken iphone 4 connected to itunes and now it does not work...How to restore it ?

Humbardi

I bought an used iphone 4 , and i bought it to use as a cheap "ipod" only for music, and not to be used as a phone. I connected to Itunes to put my music on it , but ( i did not know that it was a jailbroken iphone ) and know it is blocked by apple with " Connect to Itunes "...
Is there any way to restore it ?