I was having Esxi 4.0 host with VMs and 3 local storage devices with it. Unfortunately, someone tried to upgrade it to 6.7 but it failed with a missing ESxi 5.0 configuration message.
Upon resolving this I decided to repair Esxi 4.0 with the available Esxi 4.1 disk. The repair was a success, but am having this issue of missing datastores.
When I went to starage->devices the disk are shown, but on storage->;datastore no datastore is shown. If I choose add storage there is no option of keeping a disk data it display the disk will be formated.
Does esxcfg-volume -l show something useful?
If it does, it may be possible to mount the datastores by following the steps in the "Command line" section for ESXi versions 4.x in https://kb.vmware.com/s/article/1011387