Good Morning

I baught an iphone 4 but the speaker is not working .... whn i recive phone calls on louspeaker and heaphones i hear but when i use the speaker i hear nothing..... the person who did the jailbreak told me that he downgraded the phone to os4.0 from os4.01 .... could it be its a software issue ?

thanks

First, 4.0 to 4.0.1 would not be a downgrade but an upgrade, and second, that should not cause the issue you are experiencing. I would bring the phone in to an Apple Genius Bar and duplicate the issue. They should replace on the spot. I'd do so quickly, as well, in hopes of making sure you get a 4.0 or 4.0.1 device back from them, and not 4.0.2...

Good luck!