The bit-version is listed at Control Panel>System.
If this problem is chronic then it may be because you're running a corrupt factory preinstall - fill in your System Specs now in bottom left of post. Or you may be doing something else which is harmful such as compound tweaking, not paying close enough attention to downloads which are bringing along a lot of crapware, etc.
The steps I gave should help make this clear but if not you might be best off to do a Clean Reinstall - Factory OEM Windows 7
which steps are the same for retail. If you stick with only the tools and methods in the tutorial you will get and keep and perfect install.