Reddit secretly bans accounts it may suspect as spamming, called "shadowbanning". If your account is shadowbanned, Reddit makes it appear normal from your perspective, but will hide your posts, upvotes, etc. from all the other users on the site. You can check your shadowban status here:
You can read more about it here:
To our knowledge, Reddit does not easily un-shadowban, so you will need to create a new account.