assuming your using windows 10 or 8 or 7 , find the network icon on your toolbar (bottom right) right click on it and select "open network and sharing centre"
select "change adaptor settings" and look at your Wifi connection icon,
Does it say "disabled" if so right click and set to enabled.
if ist says enabled, try this first " right click on icon and disable" wait a minute " right click and select enable
"
if it connect back on the network at that point it could be because the network card did not reinitialise properly when coming out out of sleep mode