What make and model is the phone? If we know this we might be able to give you more specific advice.
Whomever repaired it might have done a reset to factory defaults, which would have probably erased everything on it. Were the photos on an SD-card or the phone's internal storage? If you can plug it into your PC as a USB mass storage device you could run a photo recovery tool like Photorec, which can recover erased photos. The important thing here is do NOT store anything else, if you are to have any chance of recovering them.