He will analyze and find out the problem and will give it the necessary treatment it needs. Such technicians specialize in a number of repairing services. Be it working on the hardware or on the network, they should be able to handle your problems effectively. There are two kinds of services you can experience. Some issues can be solved immediately, while some others need some time. For the later types of problems, the technicians may want to take the machine back to their workplace to have a better working environment.
There may be many problems that your computer may be vulnerable to. There may be a virus attack or some internal malfunction in the wiring system or glitches in the software. You may lose data and important files if you do not hire a good technician. So, do not try to fiddle by your own and contact the agency in such cases.