when I am typing a text message some of the letters wont work,if I am scrolling through or down something its very slow or goes on to something I never clicked on?
Assuming that you haven't jailbroken your phone, the most likely culprit is a hardware part called the digitizer. If you live near an Apple Store, you can get get a free diagnosis of what is wrong by making an appointment at the Genius Bar. The repair will not be free if it is indeed a hardware problem, but then you will have a starting place.
If you have a good up-to-date backup of your device, you can try restoring the operating system. Please be aware that the process of restoring can result in serious data loss (including text messages and photos) if you are not careful.
I have similar issue with my touch screen too. What I usually do is turn off my phone for 3-5 minutes and then restart. This works well for me and I hope it helps you too. Please read for instructions:http://www.technobezz.com/iphone-ipad-touch-screen-not-working/