My tenants moved out and still with my house keys and owe my money

[adlershelly]

My tenants rented my house for a year and many times they has been late with the payments as a result there’s nothing left from their deposit.
I know They bought a house 3 weeks ago and they “gave” me a month notice but during this 3 weeks and they moved out but left a lot of mess, and some boxes are still left and there’s a window that the glass broke and they need to fix it.
My questions are:
First I don’t know their address to send them a letter thought I know the moved quite closely to my house ,is there any web site that can give you this kind of information ?
Second I;m not very sure I will see any money from them but as far as I concern the notice wasn’t helpful if the house is still in a bad estate and I cannot bring anyone to view and they still have the keys as well (I have one but I can’t legally just come in ,right?)
And they say they will fixed the broken window but they didn’t yet and I don’t know if I should fix it? and ask for the money???

Is there any legal service I may need to use to help
Get my house back and the money they owe me? Is anyone know’s someone I can contact??
thanksssssssssssss

[MrShed]

Was the notice in writing? even if not I think the tenant would have a hard time getting you for unfair eviction with notice having been given.

Yes the tenant should be paying for all damages(including changed locks!). Tracking them down will be difficult. Do you have a contact number for them? Failing that there are certain companies which will try and track people down for you, but these can be quite expensive and do not always work...so you need to weigh up the possibility of this costing more than the damages you are claiming back.

[Editor]

Get everything fixed including cleaning and key cutting and keep all receipts so you can re-let quickly if that's what you intend.
Trace your tenants (standard fee) - see www.tenantVERIFY.co.uk for a firm that will trace them if necessary, though if you have had them complete a proper tenancy application you should already have enough info to trace them yourself.
Present them with the full bill and follow-up with a Small Claim if necessary. Providing you evidence everything properly you should have no trouble winning your case with all expenses and full costs.

[adlershelly]

first their notice wasn't in wrriten,
second, am i allowed to go into the house and change the locks? what a about their staff that left there?
and about finding their address - i mean will i find there address by the basice credit search already?? even if they just bought a house and moved in - would that be already as there current address??
thanks for your advice!!!