Search for the Instagram User

Use the search function on your Instagram app to look up their actual username. This is the most straightforward way to check if someone deactivated or deleted their Instagram account. If the profile doesn't appear at all, it could mean the account is deactivated or deleted.

However, if when you search for their account and the profile says "User not found" or "This page is not available," it may mean that the Instagram user has blocked you.

Go Through Your Messages

If you have previously messaged with the person, check your Direct Messages to see if they have deleted their Instagram account. If their profile picture is gone and their name appears as "Instagram User," or their messages are no longer visible, they've likely deactivated or deleted their account.

Look for Their Activity

When someone deactivates their Instagram account, their activities are removed, meaning their likes, comments, and posts vanish.

If you are close with the Instagram user, check for their likes and comments on your posts. You might have tagged them in your content as well.

If they have blocked you, though, their account might still be active to others.

Using a Different Account

If you are not sure whether the Instagram account you are looking for has blocked you or it was just deactivated or deleted, you can try accessing the person's profile from a different Instagram account if you have one, or a mutual friend's account. If you can see the profile from another account, you are likely blocked.

Browser Search

Another way to check whether someone deleted their Instagram account or not is by searching directly in a web browser with the URL instagram.com/[exact username]. Make sure that you are including underscores or periods as these also show up in the URL.

If you see an error message that says, "Sorry, this page isn't available" or "The page is not available," it means that the account may be deleted or the Instagram user has blocked you.

Ask the Person Directly

If you are still unsure of the status of someone's Instagram account, you can ask them directly if you know them personally. They may have deleted or deactivated their account for personal reasons. For instance, many people delete or deactivate their Instagram account due to cyber bullying or someone hacked their account. Or, a person deactivated because they may already have a new Instagram account.

It's also possible that Instagram may also have temporarily disabled their account.

Use Third-Party Apps

There are third-party apps that claim to detect whether an Instagram account is deleted or deactivated. However, please note that most third-party apps are unauthorized and may be phishing information from various Instagram accounts.

These methods can help you identify whether someone's disappearance from Instagram is due to account deactivation, deletion, or if they have simply blocked you. Remember, asking the person on different social media platforms, perhaps, might also help clarify the situation if you're concerned about their disappearance.