Which (prescription) drugs can help with massive concentration and focus problems/terrible attention span?

I had one month to study for an exam but instead of studying i was browsing the web/gaming daily for 6h+, only managed to get maybe 30 mins of focused study time (seriously think I have an internet addiction)

also I have to drink 4+ cups of coffee through out the day to get a least a little bit done

I procrastinate 95% and only work half assed 5% - I just want to be able to sit and study and not drift off into the web