Some keyboard shortcuts are universally very well known by nearly every user, even if they choose not to us them. The problem is there are literally hundreds of different and also lesser known keyboard combinations in Windows alone and it would be completely impractical for you to sit down and try and learn them all in one go. You can either go to the official website for your product to hunt for the keyboard shortcuts, or you can just go to a website that has a database of keyboard shortcuts for your convenience
ShortcutMania project seems to be pretty much abandoned with the last update appearing to be in 2011. Although the latest products from the likes of Microsoft and Adobe etc aren’t going to be here, all the titles currently listed are still fully viewable so the site still has a good deal of value to it.
The lists of shortcuts can be searched for or browsed by name or vendor. The shortcuts are layout out in categories and are easy enough to read if a little small on the font size. A useful option is the choice to download or print the list in either HTML or PDF format, although the edit button next to them no longer works. If you can find an up to date set of shortcuts here you want, ShortcutMania could still prove to be a useful resource.