regarding data in project 6

hello sir, sir currently I am working on the Bank loan case study project, here i got the data set naming application_data.csv, In this , the data is incomplete or irregular, means In column A i found count of 50000 rows and in column Z there are upto 2lakhs rows count,and in CR column count is upto 3 lakhs, there is a huge gap difference between the data, i cannot perform a single analysis in this as a i get error. like when i am performing First task of finding null values, this column A, B , C ......produces more than 2 lakh null values (formulae used :COUNTBLANK(A3:A307513) please suggest how to use this data , whether i use only 50000 rows or 3lakh rows for my analysis. thanks regards veena chandra