iMessage not working on Mac for a couple of weeks

The following poppy project forum is illustrative and brief.I want to include that I own a printing business and need to make the 3d models first at my laptop then transform it to reality.For a couple of weeks I am noticing that I am unable to take screenshot from my mac book for a couple of days.I have tried out the manual configurations as instructed by the support team to figure out this consequences regarding the iMessage not working on Mac
Suggest what to include to resolve this issue permanently.