Dear Zain,
I wont go into details here; I'll just show you the right direction. Random access and sequential access are topics from Database Management System.
Direct Access is also known as sequential access and is different from Random Access. In sequential access, the computer goes through all the records sequentially to find the one which you asked for. It is used in direct access mediums such as magnetic tape. On the other hand, in random access, the records are indexed and are accessed directly without having to go through all in the sequence. Hope this helps.