Unable to access iPhone without SIM card

If you’ve lost your SIM card, you may encounter some limitations with your iPhone, but not necessarily with unlocking the device itself. If your iPhone is already activated and set up, you should still be able to unlock and use it without the SIM card. However, you won’t be able to make regular phone calls or send traditional SMS text messages.

You can still connect to your home Wi-Fi and use most of the device’s features, such as browsing the web, using apps, sending iMessages, FaceTime, email, and more.

However, if the iPhone is not yet activated — for example, if it’s been erased or is being set up for the first time — then you’re likely to face issues. Without a SIM card, activation may not proceed, especially on older iPhones. In some cases, the phone might be carrier locked, meaning it will only accept SIM cards from a specific mobile network, further complicating the activation process.

In short:

• Already activated? You’re fine for Wi-Fi-based features.
• Not yet activated? You’ll likely need a valid SIM card, especially if the phone is carrier locked.

Contact your cellular carrier for a replacement SIM.

You need to explain what you mean by "can't get in my phone".

Carrier Lock:- Request your iPhone’s original Carrier to unlock your iPhone and if they agree and do it, then you may know the further process here --> How to unlock your iPhone for use with a different carrier ...

You may get better and prompt responses if you may kindly provide the iPhone Model that you have and the iOS version if it is known to you and re-post.

With the limited information that you have provided, It is hard to even guess the problems faced by you. 

You may get faster and better responses to your query by --> Writing an effective Apple Support Commun… - Apple ...

Please re-post with detail so that someone else can help.