1) Browse to Sharepoint Central Administration

2) Click on Operations

3) Click on Solution Management

4) Click on K2WorklistWebpart.wsp

5) If there is a schedule job, first delete the schedule job. Then click on "K2WorklistWebpart.wsp" again. Click on "Retract Solution".

6) Set "Rectract from" to be "All content web applications"

7) Click Ok.

8) Once the solution is retracted, then click on "K2WorklistWebpart.wsp" again.

9) Click on "Remove Solution".

10) Click "Ok".

Then Re-add it by running the following command found in this folder Program Files]Common FilesMicrosoft Sharedweb server extensions12BIN :

stsadm.exe -o addsolution –filename  “pfile path]K2worklistwebpart.wsp”

Remember to re-deploy it again via Central Admin .