Excel is a great tool for simple and easy data management.
But sometimes there are just limitations (of the user).
For example replace all new lines (line breaks) with some other character sequences.
It can be done, you just have to know how:
1. Open the search replace dialog
2. In the search field enter CTRL+j (It's OK, it shows nothing)
3. In the replace field enter the new sequecne (For example \n or 0x0a etc.)
4. Hit on "Replace all"
That's it, the magic is done.
Of course microsoft does not tell you this in his offline/online help (For whatever reasons)