Could an mobile electromagnetic field damage computer parts if it were place in vecinity of a computer.........??

Yes, especially wireless modems

Id doubt that a wireless modem could produce enough of a field to cause damage, maybe at best, interfere (make a little noise in a signal). Compared to the strength of signal being transmitted on the computer, the noise isnt a factor.

You aren't going to cause a spark or corrupt sectors with your wireless modem, if you could, the FTC, FCC, and FAA would be all over it, and it would never make production.

Tell that to any ISP support department (that's probably not saying much anyway!)