Player has a black screen

I've been wrestling with a problem that I haven't been able to solve for a week and a half. Whenever a player loads in, they can see character names and attribute bars, but everything else is a black screen. I've enabled Vision on his token, disabled Vision, reset the Fog of War, turned on Dynamic Lighting, turned off Dynamic Lighting, and tried solving it with Legacy lighting, to no avail. This started when I tried to give him an additional token to control, then deleted it. Now, there is only darkness. I don't know what the problem is and I want my player to be able to see the map.

Did you perhaps reset Fog of War to Permanent Darkness? If you try revealing an area can your players see the map? Have you tried changing maps between attempted fixes, to make sure everything reloads? Does this affect all your players, or just one?

Ho Whaleman! Here's a "why can't my players see anything?" checklist. The important thing is to verify. Don't assume. This list is written with GMs in mind, but can help players work through issues with their GM. The token is on the VTT It is assigned to the character The player has control over the character The token is on the Token/Object layer It is not blocked off by DL lines from seeing the immediate surroundings Make sure the player is looking at their token's immediate area. Shift-Click and hold on the token to pull the player's view to that area. If Fog of War is being used, that the area the token is in has been cleared The player has not been Split from the Party (Check the Help Center if this is unfamiliar) If Dynamic Lighting of any kind is being used: The token has sight turned on The token has a light source, or Nightvision (UDL) or personal light (LDL) In UDL it may be necessary to move the token one square to get everything working, or in extreme cases, refresh the (user's) page. Can you see a rotating cube in  this URL ? If not, the browser needs to be WebGL compatible (99%+ are). Have the player check this. If you are a Pro User, the  Dynamic Lighting Tool  script has diagnostic functions that will check many of the points above and give a report on likely causes, along with quick fix buttons. Finally, here is a guide to best practices for  Dynamic Lighting Performance .

Just to mention; verify they are using chrome or FF (only browsers supported by roll20).  Even variants of chrome (ie edge, brave, etc.) may not interact with roll20 the same as "vanilla" chrome.