Run the stsadm -o enumsolutions command from a command line on the SP server to see where and if this solution was deployed.
Thanks. I have had this happen before as well. I ran the following stsadm commands in this order. My goal was to go step by step and remove any aspect of the solution and then slowly place it back into the farm and activate it.
First deactivate the feature. Use the Name of the feature and not the .wsp name.
stsadm -o deactivatefeature -name "FeatureName" -url http://mywebapp.com
Retract the solution from the farm
stsadm -o retractsolution -name solution.wsp -allcontenturls -immediate
Run the execute server jobs command
stsadm -o execadmsvcjobs
Delete the solution from the solution store
stsadm -o deletesolution -name solution.wsp
This should give us a clean start. Now we can put the solution back.
stsadm -o addsolution -filename solution.wsp
Deploy the solution. Use the -allowgacdeployment switch if the solution needs to go to the GAC (Global Assembly Cache). Otherwise, leave it out.
stsadm -o deploysolution -name solution.wsp -url http://mywebapp.com/ -immediate -allowgacdeployment
Run the execute server jobs command
stsadm -o execadmsvcjobs
Install the feature to the farm
stsadm -o installfeature -name "FeatureName" -force
Activate the Feature
stsadm -o activatefeature -name "FeatureName" -url http://mywebapp.com
Let me know if you have questions about these steps.