Sure, nothing wrong with a fresh change and if you don't like it you can always go back to e4 or try something else. Although saying just "d4 openings" is a bit vague. Do you mean stuff like Queen's Gambit? Colle?
There's no rule saying you have to learn d4 openings if you don't want to although it would expand your overall understanding of various structures...
I really dont know, iv never opened with 1.d4 in my life. haha maybe a bit wierd but i was wondering where to start with d4.
d4 is a good idea, that's what I use as white. Study the Queen's Gambit, you can't go wrong! It's currently being played at the top levels and with good reason; it's awesome! 
okay cheers.
Ok, maybe you should purchase MCO (Mastering the Chess Openings) volume 2 which is just QP openings, and see which ones you like best. Or if that's going to take too long there's always good old Wikipedia. Once you have a rough idea of your favourites you can try and test them in few blitz games to see how comfortable you are playing the middle-games which arise and to get a better grasp of the structures.
Btw, steer well clear of advise like "play x opening". That's your own personal choice ultimately. No one knows what will work for you better than yourself.
I have started with e4 as long as i can remember, but i was thinking of starting with d4 as a sort of new start to get back into the game? is this a good idea?
Im sure id have to learn the d4 openings at some point right?