Why is my pc destop not showing only black

@aadilkaymkhani you are not giving us much to work with here. It would be good to know if anything happened to your computer or what you have checked. It would also be good to know it the computer even comes on. Anyhow, if you think it does and if you think everything else is okay, just connect an external monitor. If that shows your desktop you know your computer needs a new display or display cable etc.

Use the Acer Travelmate 290 Service Manual to work on it. Page 65 tells you how to check the LCD. Let us know what you find out.