Here's your post with some capital letters and punctuation: Imagine my car has broken down. Which one is correct? 1- The engine is not working. 2- The engine won't work. 3- The engine doesn't work. Now, isn't that an improvement? If you want anyone to take you seriously when you write, you have to write properly. Failing to do so is not an option, unless the writer is a teenager sending illiterate messages to their friends. Intelligent adults do not write without proper capitalisation and punctuation, however informal the context. Now for the answer: They're all correct, but have slightly different implications. 1- The engine is not working. ---> The present continuous aspect suggests that the problem is a temporary one. It was working before, and it's probably going to work again as soon as it's been fixed. 3- The engine doesn't work. ---> In contrast with the above sentence, the present simple aspect suggests that this is a long-term problem. In some cases, 'doesn't work' it may refer to a permanent situation. 2- The engine won't work. ----> This is equivalent to the (personified) concept of the engine 'refusing' to work. The implication is that you have tried many times to make the engine work, and each time you have failed.

Hi Davood. Any of these would actually be acceptable, but I think I would be more inclined to say "There's a problem with the engine".