how do i unhide all rows in excel properly?

Row 1 is the one that trips people up, there's nothing above it to drag-select. Type A1 in the name box (left of the formula bar), hit enter, then Home > Format > Hide & Unhide > Unhide Rows. If you see little + buttons down the left side, those rows are grouped, not hidden. Click the + or the level numbers at the top to expand them.

click the little triangle where the row and column headers meet so the whole sheet is selected, then right click any row number and Unhide. done. if some rows still won't come back they're probably filtered, not hidden. check for funnel icons in the header row and use Data > Clear.