Hello my name is***** am sorry you have encountered this kind of problem. Just to verify it's been flashing in and out and then sometimes goes black correct?
If this is the case it just means the back light is going out not the entire monitor. You can take it to any electronics repair shop or tv repair shop infact to replace the back light. Then the problem would be corrected. If you do not want to go that route you would have to replace it. That would be up to you.