Use the SelectedTab()
method. It has three overloads.
If you have a reference to the tab:
tabControl1.SelectTab(tabPage2);
If you only know the index:
tabControl1.SelectTab(1); // 0-based index, this shows the second tab
If you only know the name:
tabControl1.SelectTab("tabPage2");
You say your users can click an [x]
that removes the tab.
I'll assume it's removed by the easiest means, something like:
tabControl1.TabPages.Remove(tabPage1);
You can't focus on a tab that's not part of the tab control, so you'll have to add it back first.
tabControl1.TabPages.Add(tabPage1); // add tab as last tab in tabcontrol
tabControl1.TabPages.Insert(0, tabPage1); // or insert it at a specific index
tabControl1.SelectTab(tabPage1);