IMEI number unknown and in recovery mode, after putting sim card back in ?

Got my phone back today from the phone shop as the charger block needed replacing, as it wouldn't charge as it had shorted out.

Phone was working fine when got it back for good few hours without the sim in it, then when I put my sim in it went all AWOL and went into restore mode with message (IMEI number unknown) & (ICCID unknow).

The phone was on a contract with o2 and then after it finshed, was unlocked to any network by them for a pay as you go sim phone, which it has been for the last 18 month's.

I've read I may have to restore it but as there's many photo's, videos on there, they would get wiped off completely. It's running IOS 4. summit as never upadated due to not having enough room on my hard drive to ever put all the content on it for to do so, so I kept it the same and not backed anything up. Which I should of done but never had enough room as the hard drive pretty smal on the laptop, and the stuff on there thats important to delete to make space.

So if anyone knows what to do or can help that be great thanks cheer.