For several years after the book was left on my bookshelf untouched

after or afterward(s)? And there should be a comma after "after/afterward(s)", right?

I would use - For several years the book was left untouched on my bookshelf.

thank you!

For several years the book was left untouched on my bookshelf—I had lost my interest in it.

is the punctuation correct?
and should there be no comma after years?

There should be a comma after "years," yes.

There should be a period after "bookshelf." Then start a new sentence. You don't used dashes to separate complete sentences.

thank you for your help!

You're very welcome!

The correct word choice in your sentence depends on the intended meaning. If you want to convey that a specific number of years passed after the book was left on the bookshelf untouched, you would use "after." Alternatively, if you want to express that the book remained untouched for an unspecified amount of time and then several years followed, you would use "afterward(s)."

Regarding the comma placement, it depends on the structure of your sentence. In this case, a comma is not necessary after "after" or "afterward(s)" unless you are using them to introduce a dependent clause. If your sentence continues after the phrase, then a comma might be appropriate. Here are two examples to illustrate the use of commas:

1. "For several years after the book was left on my bookshelf untouched, I finally decided to read it."
-> In this sentence, a comma is used because "after the book was left on my bookshelf untouched" introduces a dependent clause that is followed by an independent clause ("I finally decided to read it").

2. "For several years after, I left the book on my bookshelf untouched."
-> In this sentence, a comma is used because the phrase "For several years after" precedes a separate independent clause with a subject and verb ("I left the book on my bookshelf untouched").

Remember that the decision to include a comma ultimately depends on the specific structure and flow of your sentence.