Ubuntu 12.04 can't use mouse and internet

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http://askubuntu.com – I've been using Ubuntu 12.04 for a while on my Acer Aspire One-722. It was ok, but then, after some updates, the next time i started it, an window "the system is running in low-graphics mode" appeared. I couldn't find out, what to do, so i reinstalled Ubuntu from DVD. The installation went normally, but when i rebooted, I saw it doesn't react on mouse moving, only to keyboard. It also doesn't connect to wi-fi (or i just don't know, how to connect to it without mouse). I tried to find an answer in the internet, but most of advises include downloading something, which I can't do. Thanks everyone (HowTos)