I guess you toggled mend wounds.
Invoke the Rites of Moawita, replacing your Light and Heavy Attacks with healing abilities that can only be used on allies.

I've had similar issues, normally in overland stuff, I'll be running about, dismount to kill a big bunch of mobs, and bang, I can't use anything, I can move, occasionally dodge, it's usually the dodge that frees up the abilities.
Today in a dungeon I had a similar thing, seemed my abilities weren't triggering, no damage numbers etc, however my stamina still drained..