My son is 2 1/2 years old, 6 weeks ago we went cold turkey and stopped him wearing nappies and put proper pants on him. He wet the bed the first night and that was the only accident he had! However the last week he has started to wet the bed every night! I'm unsure what to do now...have tried waking him up and putting him on the potty that's next to his bed but he still wets.
While this may seem stressful and worrying to you, your son will grow out of it. Waking him to go potty is a good idea, but you can't determine when/how often he'll need to. Some children are just heavy sleepers and don't wake from the urge to go to the bathroom. My daughter had the same issue (my son did not). We looked into bed wetting alarm systems etc., but at the end of the day, a waterproof mattress pad and a change of clothes/sheets nearby was our solution for quick clean up and getting her (and us) back to bed quickly. Good luck!
In addition to the physiological maturity as Danny suggests, it's possible that something's changed in his body: anything from an illness causing him to retain water slightly differently to a growth spurt. He might even just be a bit thirstier close to bedtime than usual.
It's also possible that he's a bit stressed out from something, or wants more attention (after all, he's lost a lot of diaper changing mommy and me time!), or something else psychological. Those largely will just go away in time, especially if there is a specific proximal cause that itself goes away.
No drinks an hour before bed (or very little sips only), mandatory potty before bed, and keep the faith (calmly!). I skipped the potty and bought a child toilet seat - works wonders for kids who feel more grown up. Lots of praise when he gets it right. And remember, boys are slower than girls - it took my boy until 3 to really get it right, just don't give up!
I've heard that adults can learn Kegels and this article mentions them for kids. Perhaps read up if you want other ideas. http://www.essentialkids.com.au/younger-kids/kids-development/a-guide-to-bedwetting--why-it-happens-and-how-to-deal-with-it-20110901-1jnga.html
Update: My assumption was that you know what Kegels are! I'm recommending to teach your child how to stop the flow of urine while peeing in the potty, so that they can strengthen the non-voluntary muscles.