Have you contacted your ISP tech support regarding loss of your LAN connection?
Have you tested it with a friend's computer once your ASUS laptop has lost connection?
If my laptop was working fine with a wireless connection, and then I rewired my network and could no longer get a reliable internet connection, I might suspect the ethernet cable, or cable to the modem, or something else I just did, rather than suspect it is a laptop issue.
BTW - What model ASUS laptop do you have?
NOTE: Not much point troubleshooting your WLAN until your LAN issues are resolved. Once they are:
What model WLAN card does it have and what version WLAN driver are you running?
Are you getting a strong signal from your router?
Are you using b/g or n?
G74SX-A1 - stock hardware - BIOS 202 - 2nd Monitor VISIO VF551XVT