As a lower-level Ranger, I can understand having energy problems. Rangers use the Expertise attribute to reduce the energy cost of their attack skills, preps, and traps. Early on, you don't have enough attribute points to keep your Expertise rank high, so you run into energy problems.
Once you have a level 20 Ranger with all 200 attribute points, you can put enough points into Expertise to make your non-spell skills much cheaper.
Expertise won't reduce the energy cost of spells.
Check out this table.
http://wiki.guildwars.com/wiki/Expertise
If you're just starting out, using attacks that cost 10 energy, you're probably still spending close to the full 10 energy each time you use those skills. Later on, if you had, say, 9 in Expertise, your 10 energy attack skills will cost you only 6 energy.
If you're trying to cast a lot of monk spells as a ranger, that's a whole other issue as folks above have already mentioned.
As to what to do, like others have said, it's entirely up to you. Play what appeals to you. Without more info, I'd say stick to ranger primary. There must've been something you liked about that to choose it in the first place. Make a new one, and make sure to get as much out of Presearing as you can this time.
Cheers!