Help In English Please

[Fatemah]

Good morning, Hope you are having a good day.
Please someone can proofread my email.
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Dear Professor,
As I have mentioned in my previous email that I’m in Siegen and I will be attending my today’s class, but I came to know that if I am not vaccinated then I must have to show a negative covid test for attending my class and some of my colleagues told me that the center where I can take my test I closed now and without a negative test I cannot attend my class.
So I want to inform you I cannot attend today’s class. Hopefully, I will be in the class next week.
I apologize for this.

Regards,
Abc

[Buenchico]

Just a general hint to writing clear English, Fatemah:
You should always try to avoid using more than one conjunction ('and' or 'but') in a sentence. If you find yourself doing so, it's best to start a new sentence instead. (There are times when that rule needn't apply, but your sentence, with three conjunctions in it, isn't one of them).

A shorter, and simpler, version of your email might be better. e.g.
"Dear Professor* [surname],
I apologise that I won't be attending your class today. I wasn't advised of the need to show proof of a negative Covid test until after the test centre had closed for the day. I will, of course, be attending your classes as soon as I've been able to remedy my unfortunate situation.
Regards,
ABC"

*Note: You should only use 'Professor' as a form of address when the relevant person actually holds that title. In which case you should include his/her surname as well. Otherwise you should use the person's correct title (such as Dr Müller) or, in the absence of a specific title, simply 'Herr' or 'Frau' (as you're in Germany), together with the person's surname.

[Peter Pedant]

' I've been able to remedy my unfortunate situation'
substitute
I have secured the relevant documents'

no contractions - - I'm = I am.....I've - I have

[bobbinwales]

Agree- great answer from Buenchico but with PP's amendment.
Your emails are understadable Fatema, but my advice is KISS (keep it short and simple) (Am not a good writer myself obvs but I can reconise good writing when i see it)

[Arksided]

I agree with Chris also (Animal) he should start a master class on good Grammar and spelling.