I have unknowingly done something to a spreadsheet which has resulted in the numbers entered in column A no longer being aligned to the information in column B and the other columns- they are one row out of place. e.g. The info in B3, C3, D3 etc relates to A2. This misalignment must have occurred during my previous session because I am unable to correct it using the "undo" arrow.
How can I correct this problem, can I somehow lock the cell entries so as to prevent it happening again and what do you think I may have done wrongly to cause this problem?