How to enter a carriage return in an Excel file
Found here:
Method 1 - Cell Wrapping
Often you only need to set the cell to wrap text, and you can set the width of the cell to whatever is desired. Choose Format Cells, Alignment tab, and check Wrap text.
The result is:
Method 2 - Insert a Return
This one's a no-brainer. Just type the first line, hit Alt + Enter and type the second line. The result is virtually the same as above, however, if you copy and paste this to Word, for instance, you'll end up with a line break. Or if you export to CSV or other text format, you may get unexpected results.
The result will be:
Method 3 - Using a Formula
To use this, you must have wrap text selected. Here's a sample formula:
=A1 & char(13) & A2
Then copy the cell and paste the values only back again.
The results, again, are the same as above. However, if you forget to wrap text on the cell, you'll see this: