hello luispa,
(i made a new thread, the old thread from last year was about cinnamon 1.7)
Your problem doesn't show up here. I guess you removed some package(s) by hitting enter without reading.
You can reinstall the cinnamon package which depends on cinnamon-session. If you want more stuff you can consider the new metapackages cinnamon-core (lean) or cinnamon-desktop-environment which is big or even huge with --install-recommends (adds +150 packages extra).
greetings
musca