You should have it pretty easy because you have 7.

Click on the start button down on the lower left corner.  The one that you click on to find programs or shut down.

There is a window that says Start Search, in that box type

restore

You will then see at the top System Restore

Click on that.

You should get a window with a recommended time to restore to.  And there should be an option to pick a different time.  Click on the different time and pick a date prior to your problem.

Use that to restore the computer to that date.  It will not wipe out any data.

This isn't a restore to put it back to original state, it just goes back to the date you pick.

That should solve your problem.

Don't hesitate to ask if you aren't clear on this.