Q147: My landlord has changed the locks and I can't get in, can I break in?
If you are a residential occupier of the premises, i.e you live there, then it is a criminal offence for any person to unlawfully deprive you, as a residential occupier, of your occupation of the premises. Changing the locks would be an unlawful eviction unless you have been officially evicted from the property by court order.
An unlawfully evicted tenant may use reasonable force to regain entry to their own home (e.g. breaking a window) though this will always be judged on an individual basis. If you had been lawfully evicted, you may be committing an offence of criminal damage. The Tenancy Enforcement or Environment Protection Departments of your local authority, or the Citizens Advice Bureau will best be able to advise you.
See the website in related information to find your local authority.