Hi Javi,
What have you done recently before this list toolbar is missing for (all) lists?
Did all newly created list and library occur this issue?
Please edit the list view page(e.g. may allitems.aspx), then edit the web part property, then change the "Toolbar Type" value to "Show Toolbar" like the following image, then save the web part property and check results again.
And you can also restore this site collection from your previous backup as a workaround, see if it works, please firstly test in your testing environment.

Thanks,
Daniel Yang
Forum Support
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Daniel Yang
TechNet Community Support
