There are many ways to be hurt in the realms, and so too many ways to
recover. The simplest is the simple passage of time - you will regain hit
points slowly as you move or stand about, more quickly if you are resting,
even more quickly if you are asleep. Each time your hitpoints increase, the
damage to your limbs will also ease somewhat, unless they are severed, or
simply bruised.
The other main way to repair damage to yourself is through magical means -
the healing prayers of priests, quaffing an elixer or potion, or using a
magical device.
For those in need of rapid healing without prayers of their own, many priests
throughout the realms will aid those in need. Many NPC priests will 'heal'
you if you make a donation to their church.
* Note that healing and hitpoints are distinct from physical exhaustion and
stamina points. While there are magical means to address the latter, none
save the most powerful healing spells will also ease fatigue.
* Most diseases require professional attention to be resolved. The sooner
you can get such, the better.