My compaq presario f700 has a blank screen, power working

muzammil , the first thing I suggest you try is to attach an external monitor to it. If that works, you will at least know that it is not a reflow situation. Then the problem is with either your inverter, your LCD or your cables. If it does not work, you could consider a reflow. Problem with that, it is not as easy as it might sound. If you never have done one before, I would definitely take the time and work on some old boards first. Make sure that you have the right tools (sorry, hair dryer's are not the right tool) You need to be able to control temperature for a set amount of time etc. Take a look at this this video for the professional approach and this one for a more home made approach. I recommend you look through this note. It does explain it pretty good. This is not to say that an oven or a hot air gun will not work, but it will not be as accurate and thus has a higher degree of failure. Hope this helps, good luck.