Hey everyone,
I have exactly the same problem, still ongoing. I was trying to make space on my phone, so uninstalled Google Play and Google Services as deeply as I could. (Then I removed my external memory card as it broke)
A few weeks later started noticing the same problem: I could not download and install any app whatsoever. (Other parralel problems were constant annoying phone failures such as "Sorry, Whisper push has just stopped working" etc...
I recently reset my phone to factory reset, and tried to follow the advice above. However, I do not have GooglePlay listed anywhere in my "settings-apps-all" tab - I really think I managed to uninstall it completely. And now I can't reinstall GooglePlay despite my best efforts. Any ideas please?
I have a samsung GT-I9000, running CyanogenMod v 11..., Android 4.4.4.
Thanks!
p.s the solution is to install "Google Apps" from the cyanogenmod wiki site. Problem solved!