I have inherited a number of spreadsheets where the previous user closed rows by dragging the mouse up the table and collapsing them. I have found no way to open them except by looking for each line and opening them individually. This has become painful with 600+ row sheets where I have to scroll down and look for groups (and sometimes a single one) of rows to open...one row at a time.

Is there a shortcut or command to make these open? The hide/unhide option is not working in this instance.