Find cell and copy value to column to the right

[Ixtreme]

Hi,

I have an unsorted list with data in columns A:J. I would like to
lookup a value that is listed in column K. If the data is found, the
value directly to the left of the found cell should be listed in
column L. If found more than one time, the information must be
separated by a comma.

A B C D etc K L
100 101 102 103 etc 102 101

Thanks

 

[Ixtreme]

Things have changed. If found, I need the value(s) that is (are) in
column H.