Can anyone help me?My motorola phone is not working after trying to modd it

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I'm not that really familiar in modding motorola phones.I tried to add gmes on it and even try to install iTunes. I downloaded softwares to add itunes,getting connected with my pc,but when i turned my phone on it is not working anymore. I got tutorials online to make sure im doing the right thing but it turns out bad..but now i sent it back to the store where i bought my phone.They said that they are going to upgrade my phone.Well that's good though but my problem is"the reason why i bought it is because i want to install games and mp3s and videos,I ask the store attendant how will i install games using my pc,but instead they just advised me to download games through my phone or by loading games directly using my phone but that will cost me a lot and its just a waste of time..Can anybody help me on this?