1) I want to ask about the food which is available in some of the restaurants in Europe which do not offer halal food but still it is from the halal animal.

2) If they slaughter animal in islamic manner means they used to cut head but do not take anybody’s name while cutting it. So it will be haram too?

1) It must be halal means slaughtered in Islamic manner.
If not then it is haram.

2) It is haram.