error 0x80042302 in recovery, inability to connect to the internet, audio unusable, toolbar and windows style windows '98, inability to change settings and use boot recovery at the starting

I state that I have a Dell Inspiron N7010 with Windows 7 Home Premium.
Yesterday I followed a guide microsoft to speed up your PC, precisely this windows.microsoft.com/.../speed-up-your-pc, in particular I run disk cleanup and uninstall old and unused programs including an antivirus downloaded on the same day (avira antivirus free) as the previous one did not satisfy me most (advanced system care free). To complete the uninstall I was asked to restart. when it estarted, displaying aero style windows and taskbar was no longer present and even be set using the theme customization. In addition, the audio is not working and you can not connect to the Internet. Any attempt to change settings through the control panel seems compartment. Specifically settings and system files restore because of an unexpected failure of a component of the Volume Shadow Copy Service (0x80042302). I sought clarification of this error on the internet and the only solution seems to access the recovery when windows starts and proceed to recover using this procedure. However when I press F12 at the starting to open the recovery boot, the computer seems to stop and remains so until you press Esc.
I have no idea what happened and what to do. I need a hand