If the police have a search warrant, then they are allowed to enter your property. The warrant may restrict them in some ways, such as saying they can only go into a specific part of your property, that they can only carry out the search at a certain time, or that they have to look for a specific type of evidence.
If they do not have a warrant, then the police may ask for your consent. You can provide it, giving them the ability to enter your home. But you can also refuse to give them consent. If you do, then one of the only ways left for them to enter the home is in an emergency.
No time for a warrant
The issue with an emergency is that there isn’t time for police officers to go through the lengthy process of getting a warrant. Maybe they were chasing a suspect. Maybe they claim they heard gunshots inside the house, so they thought there was a risk to the public. Maybe they claim that the evidence they were searching for was actively being destroyed. In an emergency, they can sometimes enter the house without a warrant or consent.
But what if the police lied about the emergency? For instance, maybe they forced their way inside because they said there was a danger to the public, but there were no firearms in the house and no one in that house had even broken the law. The police just invented the issue of a “danger to the public” so that they could get inside without consent.
If this is what happened, then it may invalidate any evidence that they gathered. Take the time to carefully look into your criminal defense options.