How to solve internet connection problem on Linux Mint 15?

Question

linux

I congratulate everyone on the past holidays :) But that's not about that now.
I've been sitting on Linux Mint 15 for half a year now, everything suits me, but the Internet disappeared a couple of days ago: there is no ping, firefox also behaves strangely - instead of going to the site, it offers me to save the bin file. Another oddity is that there is a wifi router (tp-link wr740n) and I can access the Internet from a laptop without any complaints (windows 7). Does anyone have any ideas how to fix this? Thanks in advance.