About my desktop

Hello,
To you all sir/madam i have aproblem with my desktop icons and even the start menu they disapered from morning and i have tried my level best but have failed all so i would like you to help me for that anothe problem is that i have an internet but some computers keep on disconnecting themselves and others remain on the net i would like to know the cause the next problem is my scanner has failed to scan on the computer which is installed when i put it on it realy starts but as soon as it begins to scan then it swicthes it'self off.

Thank you...................