Health Bars Disappeared

i was in a ranked game like normal, and after alt-tabbing to change my music playlist, i got back and there were no health bars anywhere, i couldnt see health, mana, nametags, or the red/blue highlights around enemy/ally players. Someone on the enemy team suggested I press alt-z and it did nothing. After going through my settings to see if i accidentally disabled health bars, i had to restart my client. about 5-10 minutes later this time without alt-tabbing, the health bars disappeared again.