Could you correct my words? I really want to speak english fluently

Good job! You don't seem to have any actual grammar errors here, but I could make comments on a few places where word choice can be a little bit misleading. You've used the same type of past tense through the whole story. When I was reading this, I thought that it was very recently that you still needed an interpreter. However, then it seems all of a sudden that you've skipped forward a lot of time, to a point where you can speak English effectively. A simple fix could be to give some indication at the beginning that this was longer ago, or isn't the case. Like "When I guided factory tours, I *used to* do it with an interpreter." Another possibility: "Previously, I guided factory tours for foreigners with an interpreter." This is very minor, but when you say "It wasn't until today that I knew the interpreter would not come" instead of saying "knew" I would say "found out." "To find out" does a better job of implying NEW knowledge. Lastly: "I should have studied english hard." I believe "harder" serves the purpose better. Because you probably had studied English a little bit already, but your need was to do a BETTER job, so use a comparative word. altogether pretty good! Keep it up!

The other comment does a good job of explaining what needs improvement, but a couple of small things I would add are towards the end. It would be best to say "... but once I got used to guiding tours" instead of "tour" (singular). The other thing is to add a comma instead of period between "... without an interpreter. It wasn't that hard." It's better to add a comma here since these aren't two separate thoughts.

Occasionally, I guided factory tours, along with an interpreter. One day, I had a tour scheduled, but was not informed ahead of time that I would not have an interpreter. \[I'm not actually sure what you are trying to say with you should have studied English\] It was difficult at first and took some time to become skilled at communicating in English; but once I got used to giving tours without an interpreter, it wasn't that hard \[there should probably be an end here, because it is rather unclear what wasn't hard\].