Unable to log on to Administrative Account

Hello there,

I hope I am not going to lose all of my files.
Last night the system (Vista- Home premium 64 bit)did some regular updates. This morning, when I tried to log on to Admin Account I got the message : The user profile service failed to log on. user profile can not be loaded.
I do have other account and I have already tried to fix the thing using some recommendations that I have found on this thread and other places, but I have another problem. It seems that most of the exe system files from my other account are gone. When I try to run a program which will supposedly fix the thing, I get the message to choose the program to open it with. And then I am stuck.
Just to note, when I tried to open MS Word or any other program, it prompts me to choose the program to open it with. Strange. I do not know what did I get myself into but I hope I will not lose all of the documents I have stored in Admin Account.

Also, computer was bought in Office Depot and they did the instalation for me, so I do not have the disc.

Any suggestion will be appreciated!

Already tried it this morning, but even when I am looking for redegit, it says it can not find the file.

Yes , you are correct "regedit" but it says Application not found

Thank you so much for your help. It did work. I am able to log in without any problems on my Admin Account. Still, the executive files are missing from my User Account.
I am wondering now, what can I do on my part so this thing does not happen again?

I will just describe what happens. This is a poblem that exists since summer but I was in the mist of taking online classes and did not have time to take care of it then ( I may pay now for it!). At that time I also just did the regular system update, and ended up with many problems.

If I try to launch Internet explorer , I get the window asking me to choose the program to opent it with (iexplore.exe). If I click on Internet Explorer icon that is listed as one of the recommended programs I get window to run or save the file iexplore.exe. If I click Run it just goes back to "Choose the program to open it with". If I choose Save, then it only saves it in one of my folders and do nothing after that.
If I choose Desktop shortcut for let's say Word, it says "Application not found". It also does to Skype,, which I tried to reinstall several times but nothing helps - Skype and everything else work on Admin Account.
If I choose Word from Start menu I get this : This file does not have a program associated with it to perform this action. Create an association on the Set Associations control panel. But I do not know how to do it.
I tried today to reinstall things using the instalation disc for Microsoft Home and Office but it was unsuccessful because I had to go through the proces of choosing the program to open it with , and I was stuck again.