Stolen Iphone, Find My disabled and Apple ID pass changed.

If they disabled Find My – because the phone was unlocked, or because they obtained/guessed your credentials – there's no way of remotely turning that back on.

However, you can still report the theft to the police and to your phone company (carrier).

Many carriers put the IMEIs (unique identifiers) of stolen phones onto blacklists. If yours does, then any carrier that honors your carrier's blacklist will never offer cellular phone, text message, or data service to the stolen phone ever again, absent the sort of proof of ownership that the thieves and their customers will not have.

Since the thieves changed your Apple ID password, that implies that your Apple ID has been compromised and that you need to take steps to secure it.

If you think your Apple ID has been compromised - Apple Support

If they have gotten into your phone, they also might have accessed any personal or financial information which you have stored there. So take appropriate precautions against identity theft.

MonicaDra wrote:

I went to the Police and they have told me that after 10 days it will be considered stolen. At the moment it is just lost in their opinion.

I have the box, therefore the Imei and serial number, so I thought i could report that with Apple and they can block it or do something.

Apple doesn't blacklist phones based on the IMEI. That's something the phone companies do. Contact yours. If the thieves have already disabled Find My, the loss of cellular data connectivity to the Internet won't make the Find My situation (can't track the phone / mark it as Lost / request an Erase) any worse, but the blacklisting will partially "brick" the phone – effectively downgrading it from an iPhone to an iPod touch.

Once the phone company blacklists the stolen phone, watch out for "phishing" attempts from the thieves aimed at getting you to un-blacklist the phone. Some thieves are brazen enough that they contact the owners of stolen iPhones, pretending to be Apple Security (or some such) in an attempt to get Activation Lock released. They may try similar stunts to get you to have the phone un-blacklisted.

MonicaDra wrote:

the person managed to disable my Find My and chanced my Apple ID password.

If the above is true the only option that you have is to report the incident to the local law enforcement authorities before the device is used for criminal activities.