Is the PC really looking for the Brother printer?
And if the printer was on a network and you just changed to a physical USB connection without the necessary configuration changes (i.e., network to USB) then the printer will not be found.
Check if any other computers are able to print. If so then match your PC to their printer configuration.
If not, then go into the printer's menu screens and make sure the printer is still configured for your network.
Perhaps some update either on the PC or the printer, has gone astray at the expense of connectivity.
Last, just start over and reinstall the printer drivers on your PC.