What should I do if I need to enter Thailand to retrieve my possessions during a visa run?

Hard but not impossible.

You can easily get insurance but the certificate may be costly.

If you can, maybe fly to South Korea and get tested there. South Korea tests aggressively and is still open AFAIK

Do you know anyone in Thailand? Maybe ask a friend to assist or your landlord of the property you are renting from.

Embassies won’t assist you as you are not even in the country. They only take care of affairs from the country you are in.

Nope they don’t care about your personal effects...sorry but it’s the truth

> Is there any reprieve with embassies, for example about entering just to retrieve possessions?

No there isn't.

>and not sure I can find it before my flight on Monday

Good news, *THAILAND* has not closed their borders, and you can still cross by land (*FOR NOW*). I don't know what your nationality is, and if you haven't done your two border entries by land, AND you're from a visa exempt country, go and enter Thailand from a land based border. I recommend

1. Contacting the local Laos consulate and purchasing a tourist visa

2. Enter Laos by air, in Vientiane.

3. Enter Thailand by land across Friendship bridge.

4. Take a domestic flight to where ever.

That'll give you 30 days with the ability to extend it by another 30 days at immigration.

You may be able to get an eVisa to Myanmar, and cross over that way too, but the border is a bit more strict :(

You have to have the medical certificate stating negative and have good medical insurance.