My iPhone 4s screen is glithcing anf flikering but cant see the screen

If you're lucky you may be able to fix it by reseating the display connector. Changing the screen is quite difficult on the 4S if you haven't done this sort of thing before because the ribbons pass through a narrow slot and are very easy to tear as you try to feed them through - I know - I've done it!

You will need a set of precision screwdrivers. Always press hard to loosen screws so as not to damage the heads - quite easily done. (See https://therestartproject.org/wiki/How_t...)

Follow the guide for rear camera replacement at iPhone 4S Rear Camera Replacement

You'll need to disconnect the battery but you needn't remove it - it's stuck quite firmly with glue.

Having removed the cable cover plate in step 10, the display data cable is the one to reseat. This is shown in iPhone 4S Screen Replacement step 17. Having lifted it off it needs to be precisely aligned to get it back on. This will take a little patience, but don't worry, it will go back! Don't try to force it or you might damage it. You will feel a positive click when it engages. Make sure both ends are engaged. Make sure the other connectors haven't been dislodged.

If this doesn't fix it then I'm afraid it's going to be a new screen.