Adobe never removes old lens profiles. Why would they do that? If your lens was ever supported, it should be in this list: https://helpx.adobe.com/camera-raw/kb/supported-lenses.html . If it is not, then you probably do not remember it correctly.
Alternatively, a user lens profile may have been created in the past (or downloaded, that another user has created). This would need to be transferred e.g. into a different computer: it would not have been automatically installed along with the software.
Next, lens profiles refer to a particular camera model as well as to either Raw or non-Raw.
Separately, if such a user lens profile is present it will not have been included in the supplied auto-lens recognition. It can be manually selected; if not, then it is not in the right place or the current image does not support having that profile applied. Anything other than an Adobe original supplied profile must be saved into the user profiles area: it will not be seen if put into the central folder where the Adobe supplied ones live.
In order to have the lens profile auto-recognised for new imports, two further steps are necessary: the profile must be set as a user-custom assignment via a sample image (from that camera, with that lens) for which this profile has been manually selected; AND the default processing applied to all new imports from that camera, must include "Default" lens profile selection rather than "Auto" lens profile selection. Auto would disregard added user profile assignments, only employing Adobe's built-in lens recognition.
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