Hello,
try powering down completely by removing power cord and battery. Leave of for about 2 minutes.
Try to turn on. If it asks start up normal. If this doesn't work, retry and when asked start up in any safe mode possible. If you do get in try to run any type of anti virus program. If this still doesn't work you might have to find your restore disk an try restoring your pc back to its original settings. If you have your operating system disk it might be able to repair the problem with out loosing all your data.
Hope this Helps

If one of the options is start windows normally, just push the up/ down arrows to get to it, then press enter and it should go to normal, make sure you push enter, if it doesnt work, turn it off then back on and try it again