My acer aspire one wont boot and is showing "insert a boot disk and press any key"but there is no disk rack on it.what do i do.

It sounds like the boot sector of your hard drive has become corrupted. if you have an operating disk with your operating system on it [xp, vista, whatever] insert it in your cd drive, and select 'start windows with cd support' NOTE- if you still get the same message, you may have to change the boot priority order- this is done as you turn the machine on, and it will say 'press esc, or fi, or some key to enter cmos [or bios setup] usually that choice appears under advanced settings, look for 'boot sequence' or 'boot priority' -select cd rom. then try the first steps i described. if you are able to access any work you may have saved on your hard drive, BACK IT UP !!! - use a usb jump drive, or if your able to, on cd;s [if you have a writer] the reason i say if your able to, is there is a possibility that all the drivers necessary to write cds might not load. there is a possibility that you might only get the options to install windows, or repair previous installation. try repairing the installation first, but be advised there is still a chance you may loose any saved work. if this happens, do a new install, making sure that you choose the option to allow you to choose the size of each partition. make at least two partitions [which will give you as many drive letters, usually two is sufficient] and install your operating system on 'c', then as you use your computer, make directories on the next drive letter, and install programs that give you a choice on the second drive. that way, if your operating system ever crashes again, you only need to repair/ re-install it, and the information on your next drive letter is saved! many computers come with 'rescue disks' - this will in all likelyhood work, but it will return the computer to the way it was when you purchased it- anything you've added since will be lost! good luck