How can I obtain a deleted track from SoundCloud?
Unless someone else has downloaded the track you are looking for before it was deleted, which is unlikely and shouldn't be relied on, it is not possible to obtain deleted tracks from SoundCloud.
Some people will share their downloaded tracks on Soulseek or VK. If you're desperate, those are your best bets.
Is there a SoundCloud archive?
No public SoundCloud archive exists.
Where can I find music?
What formats does a streaming service provide?
How can I check if a file is MQA?
You cannot reliably check for MQA. Simply reencoding an MQA file removes the MQA syncword, which makes the file undetectable by MQA identifiers.
Is Album Art Exchange (AAE/AAX) down?
Most often it is not a question of, "Is it down or not?", rather you should ask, "Is my IP banned or not?" as many countries and VPNs are banned from accessing the site. The owner cannot be reasoned with, and interaction with them and their site should be avoided entirely if possible. See Finding Artwork