I don't know why but I can't edit tag info at tag page.
edit tag button (which was available in the past) I see next links:
history | show excerpt | excerpt history
And no another button or links. Why did this happen? Any suggestions?
You are currently blocked from suggesting edits, which includes tag wikis and their excerpts. Your block clears in 5 days.
Your recent suggestions for tag wikis all plagiarize content from external sources. Users caught on and started rejecting, which caused you to get blocked. Please don't do this.
Tag wikis should explain what the tag means to the community by providing general information (usually summarized) on the subject, as well as how the tag is meant to be used on the site. Copy-pasting blocks of text from external sources is rarely ever needed. They do not exist to create cloned pages from Wikipedia.