lookup cell info and returning line info

I need some help with a formula please. Here is what I am looking to do:

I have data inputted into cells a-o in rows 1-250. I want to search, lets say row 1, (I do want to search all 250 rows if that info is relevant!) and if cell m is blank then I want to return all the info from row 1 into row 260. If there IS data in cell m then I want to return nothing. Bottom line I want to return all the data in all the rows that contains nothing in cell m.

I know a little about excel but this is just beyond my knowledge.

Please help with a formula that could perform this function for me!

Thanx a billion!