I have an installation (3.4.8) who it's missing com_joomlaupdate component. It has removed. It has upgraded from a previous 2.x version.
Can I reinstall manually? Or how can I fix situation?
The install package for the Joomla Update Component can be downloaded and installed as you would with any extension.
Joomla Update can be downloaded from:
https://github.com/joomla/joomla-cms/releases/download/3.6.1/com_joomlaupdate-3.6.1.zip