Hello again and many thanks for getting back.
I had looked up how to reboot as well as how to deal install avira but my complete laptop ends up frozen and every key I touched came with a warning ring.
In consequence I have had to give my PC to the PC repairers and they will de install a view and substitute it for another antivirus . I am writing this from a tablet.
However I would like to thank you again for all your help and i would have tried your recommendations before my PC decided to stop completely.