If an image has been photoshoped, is it possible to find that out? what method or software should I use to find it out. And also how do I find out the source of an image, like what camera or phone was the image came from? and can this information be tampered? what method should I go through or what software to use to get these information?

I bet there are forensic courses for that kind of job

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SAN, NAS, RAID, Server, and HDD Data Recovery.

This tool is useful for JPEG based formats:

http://www.impulseadventure.com/photo/jpeg-snoop.html

thank you! i have never used this kind of software before and don't know what to look for for info, I hope it easy to figure out.

i think it is impossible to recover a photoshoped image

a) That statement is incorrect.

b) That is not the question which the OP was asking - the question involved detecting image manipulation.