I've just bled my brakes and there's no stopping power in them, have I still got air in them and need to do them again?

Does the lever feel firm or mushy? If it's mushy you probably haven't bled them right. If it's firm you've probably got fluid on the pads, which may or may not be fixed without new pads…..

mushy, looks like back to bleeding! thanks!

yeah, make sure you tap the tube as youre bleeding them do dislodge any airbubble in the caliper/lever

What brakes are they?

if you can, take the whole system off your bike and hang vertical ( spare handlebar or the likes helps). open bleed nipple on lever etc. leave them overnight after giving a good tap. a right faff but usually does the trick if your having probs.

ice on your rims?
Thats what was causing my loss of braking this morning 🙂

Thanks everybody. I'll try the tapping of the tube because I was pretty sure there was no air left in-must've missed some though!
pp- the brakes are hayes stroker trails.

Sorry, Hayes are one of the few brakes I've not bled! 🙂

I was going to say frozen fingers? (or lack of fingers)