Qualcomm QCA61x4 Wireless Adapter not working

I just recently installed windows 8.1 because I hated windows 10, it ran my computer so slow that's why I downgraded and when I downgraded my wireless card doesn't work it's a Qualcomm QCA61x4 like I said and it shows but doesnt work I have no VPN installed when I installed win. 8.1 it just quit working it doesnt even show a WIFI icon it only shows the Ethernet thing and the fever says incompatible or something like that whenI click properties help please this is a schoo computer and i need it thanks to anyone who helps, no rush