The problem can be your monitor, video card, video card driver and your motherboard, try the following step and identify possilble problems.
1. bring your monitor to any fried who has a PC, if it does not work on your friend's computer, then your monitor is not working, buy a new one.
2. if your monitor is working fine at your friend's PC, then depends if your video card is a dedicated video card. If it is a dedicated video card, install it to your friend's computer again. If it is not working, then buy a new video card. If it is working, then it can be quite complicated. Try step 3.
3. if you video card is not a dedicated video card and has a free video card slot, try to borrow a cheap video card from your friend. If it is working, then buy a new video card.
4. if everything fails, then it may be your motherboard which has problem.
1. bring your monitor to any fried who has a PC, if it does not work on your friend's computer, then your monitor is not working, buy a new one.
2. if your monitor is working fine at your friend's PC, then depends if your video card is a dedicated video card. If it is a dedicated video card, install it to your friend's computer again. If it is not working, then buy a new video card. If it is working, then it can be quite complicated. Try step 3.
3. if you video card is not a dedicated video card and has a free video card slot, try to borrow a cheap video card from your friend. If it is working, then buy a new video card.
4. if everything fails, then it may be your motherboard which has problem.