Due to the reason drive was full its possible it moved on to the default location on C:\ in temp folder . I have seen this behavior with ULS Logs.
Resetting index does not change the index location.
Make sure you have drive big enough to host the index files, reset the index and start the crawl . you should see the index populated on D;.
Use the PowerShell to make sure index location is same as D:\ in Search service application.