If your keys are 'literally' sticking then the keyboard will have to be repaired but if you are just getting multiple entries when pressing keys see if altering the following settings helps.
Go to Control Panel (press Win key + x key together, select link) > Ease of Access Centre > Make the keyboard easier to use > Set up filter keys > Filter options. Try altering the two options offered and see if this helps you.
Here is a link to the service manual for your laptop.
This link, taken from the manual, shows how to remove the keyboard. Click on the next page link at the bottom of the page to view further instructions on keyboard removal.
This link shows just one supplier for an "English' (US) keyboard. Depending on which manufacturer's keyboard that you already have will decide which one you might wish to obtain as a replacement. (See last paragraph). They all obviously fit and work the same but there may be a different 'feel' between the old and the new keyboard if you get a different maker's keyboard. (Obviously Lenovo must sub-contract for their parts)
I think, (don't know for sure) that the keyboard part number should be either stamped on the underside of the keyboard and possibly the maker's name also, but the part number will tell you this anyway or it will be stamped on the keyboard flex cable which attaches to the motherboard. There may be other suppliers that suit you better. Just 'Google' the part number for the keyboard (for the appropriate maker/language) found on this page of the manual to get suppliers of the keyboard. Again, just click next page link on bottom of page to view more details
Hopefully this will be of some help