excel 2021hidden rows

in this case, move your cursor to the top side hair line (joint line of 10th & 11th line), the cursor shape will be change in black 2 parallel vertical lines and up and down black arrow. then double click on this hair line again and again, I think it will be unhide. Other way is click in the Name box just top side of 1 line where reference of rows and column combines, enter there A1 and press enter. then continue press Shift Key on Keyboard and move the cursor to down by pressing down arrow key without leaving Shift key and then press space key once. by doing this, from left to right entire rows gets selected, then right click by mouse or keyboard's right click button and press unhide, if it is not getting work, then do same process after right clicking, select Row Height and give 20 or more space. I think it will resolve your query,