Hi Sam.,

Yesterday was a good day.

Can be: I enjoyed yesterday.

I have spentd an excellent time and hope we would repeat itcan do it again.

But there is one problem.

Can be: However, there is one problem. Typically, we avoid starting sentences with "and" or "but."

When I left your home and came home, I realized that I might have forgotten to take anmy phone's external battery pack for my phonat your house.

Can be: When I got home, I realized that I might have forgotten to take my phone's external battery pack at your house.

I think ithere is on the table which is in the bedroom.

This thingIt is important to me because I often attendgo to places where there is no electricity to charge a phone.

Can also be: It is important to me because I often go to places without electricity to charge a phone.

I plan to come over tomorrow and would like to know if you will be home at 11.00 a.m.?

"I plan to come over tomorrow. Will you be home at 11:00am?" sounds more natural to me.

Roman.

Hi Sam.,

Use a comma instead of a full stop after addressing someone at the beginning of an email/letter.

I have spentd an excellent time and hope we wouldill repeat it.

Because you are referring to 'yesterday' (i.e. "I had an excellent time yesterday"), you must use the past simple (had/spend) rather than the present perfect (have had/have spent).
'Yesterday' is a finished time period - it started and ended in the past. We use the present perfect tense with finished time periods.

Also, we use "will" with "hope" when talking about the future. If you use "hoped" in the past, you can use "would". (E.g. "I hoped we would meet again.")

When I left your home and camegot home I realized that I might have forgotten to takeleft an external battery pack for my phone.

If you say "I got home", we already know that you left Roman's house, so you don't need to say both of these things.

Also, "left" just sounds a bit more natural than "forgotten to take".

I think ithere is on the table which is in the bedroom.

I plan to come over tomorrow and would like to know if you will be home at 11.00 a.m.?

Just a note: your sentence is not a question, so in standard English it should not have a question mark (?). But, as it sounds like a request, many people choose to use a question mark in informal language. As the rest of your letter uses quite formal English, I would suggest not using a question mark here.

Roman.

No full stop (.) required after your name