A little more observations would help. Does it have a disk activity LED. If so what does it do after the logo disappears.
Here is what happens:
On power up the computer reads and executes the BIOS. The BIOS displays the logo and tells the CPU how to read the boot sector of the drive. If it can't read that nothing happens but it will display a message. If it reads it, it will load the OS. The disk activity LED will blink rapidly and constantly until it is complete.
If it never boots up, the possibilities are that the drive is not functional or that it is not readable because of file corruption. The fact that it was slow before this happened strongly point to a problem with the drive.
You can try doing a repair install of Windows. If that doesn't work, it is time for a new drive.
If you have a backup of your stuff, great. If you have a recent image of the drive, it is painless.
Otherwise, if you connect the drive to another computer externally and the computer sees it you may be able to retrieve your stuff.