Connecting another PC to the router by ethernet cable couldn't cause your Laptop's "wireless" not to switch on.
Try unplugging the mains lead and remove the battery, so that the Laptop is without any power. Leave for about 30 minutes. Reinsert the battery and see if the wireless adapter stays on.
Presumably the battery has a good charge? It may be that, if it is very low, "wireless" is intended to switch off to conserve power, although this shouldn't happen with the mains lead/charger connected.