That is not a particularly old laptop ASUS - Notebooks- ASUS X54L
And it lists it as having only one RAM slot in the specs.
This would have also been in your user manual. After all else fails, please read your manual.
It would be helpful to know what screw you removed.
It would be even more helpful if you could describe exactly what you have done, and provide some pictures here.
It is very hard to give advice when you do not have much factual information to go on. With more information we may be able to help you repair it yourself.
Given that you do not seem to be very experienced with the hardware side of laptops (I'm not trying to be rude, it is just my observation based on what you have said here) my best advice would be to take it to a repair shop. It should be a simple, low cost repair given what you have told us, and might end up costing less money than doing further damage inside your laptop.
An alternative would be to call in a friend or relative who you know has actual experience doing these kinds of repairs.