Wow.... it doesn't look like Toshiba is going to make our jobs easy.
Have a look here
http://support.toshiba.com/support/modelHome?freeText=3574909
select the "drivers and updates" tab
select your operating system as well as system architecture (Windows 8.1 32bit or Windows 8.1 64bit) from the left column and see what is provided in the way of Driver Software for your wireless card.
Just skimming through, it looks like that model may have came with a variety of possible wireless cards installed. I see a driver for a Realtek, an Atheros and an Intel as a possible selection.
Unless the choice is obvious to you maybe we could determine something more specific from the Hardware IDs.
Open Device Manager expand Network adapters, select then right click the problem wireless adapter and choose properties.
Select the Details tab, use the drop down arrow to change Device description to Hardware Ids
In the value box right click and choose select all, then right click again and choose copy.
Paste that information from the clip board into your next post and we'll see if we can help you find a driver
Should look something like this
PCI\VEN_10EC&DEV_8168&SUBSYS_E0001458&REV_03
PCI\VEN_10EC&DEV_8168&SUBSYS_E0001458
PCI\VEN_10EC&DEV_8168&CC_020000
PCI\VEN_10EC&DEV_8168&CC_0200
but not necessarily exactly.