Windows Defender Error

I keep receiving a windows defender error after startup. Somehow it seems that windows defender is unable to run due to some kind of issues—looks like it is disabled. I am not even able to run a scan. Any suggestions? Thanks

IMHO WD is not any good so it in itself is not a bad thing to ditch\block, there are free alternate options far superior available, but that said if this has started happening suddenly without any reason then we need to check if you may have other issues going on. You don't mention what OS your running, nor what scan(s) you have tried, this info is pretty important to us to gauge what may be going on, this may be an infection issue best dealt with by the pro's, but would like to confirm 1st as they are pretty busy guy's, and no point creating extra unnecessary work for them, so if you could add this info it will help us to decide the best way to help.