CTRL+Home takes the cursor to the start of the document and by default the Undo command is on the QAT (Quick Access Toolbar). It seems you may have a problem with your normal template. Start Word in its safe mode (Hold the CTRL button while starting) and check that both commands work.

__________________
Graham Mayor - MS MVP (Word) (2002-2019)
Visit my web site for more programming tips and ready made processes www.gmayor.com