My aplio 500 is running very very slowly

Let me expose this problem, but please have the patience to read it because it is too long. To install a B/W Sony printer on my Aplio 500 ,i called a "technician". Before doing this, he opened the machine and accessed the hard drive and told me that he will take a "system image" or "system copy" in anticipation of any possible malfunction of the machine in order to restore its normal functioning. I said you can have a backup without opening the machine, but he said it was the same thing. It was a bit weird for me but he continued to copy the "image system" from the hard drive and he did not listen to me. Then, he moved on to installing the printer and took three hours to do it (weird again!). When we restarted the system, many dialog boxes appear. Given this problem, he tried to restore the system by opening again the machine and plugging his small disk which contains "the system image" taken before. But he had trouble restoring the system. So he took the machine to his workshop, and after three days he returned it to me. But to my surprise, the printer was really installed, but the machine was running very very slowly and i access with difficulty to my archives because it takes a long time. In addition, the machine takes a long time to start (and a message "please wait" is always appearing) I don't understand what is happening but "the technician" tells me it's normal (!). No backup was given to me but only a copy of the famous "image system". Please, how to repair this?