Sentinel Activation Button Missing/F2 Button Not Summoning Sentinel

came home from work, started killing monsters, went to activate sentinel with F2 and noticed nothing was happening as well as the button thats usually on the bottom right near the skill slots is also missing. not sure if i hit a button to hide it all but i have tried everything i can think of from searching forums for answers to checking all of my sentinel skill tree and making sure my sentinels have charges and even switching and trying every sentinel i own.