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Hi Akash
Your formula in cell J3 is "=SUMIF(B2:B17,$B2,E2:E17)" but should read
=SUMIF(B2:B17,$I3,E2:E17)
. (Your version summed values in E2:E17 that match B3 "Akash" so changing the drop-down in I3 didn't alter the sum in J3). I've done that in the attached file.
Also the dropdown in I3 could be simplified if you did data validation based on a separate list (without potentially many duplicates). In the attached I've illustrated that in $J$9:$J$17 and applied the same data validation in I3 to B2:B17 too.
REVSION NOTE: The attached file now has my data validation list in alphabetical order (followed by potential new employees) for ease of selection. Also corrected cell references in second paragraph.