Sometimes because of some customizations or when you’ve worked with SharePoint designer, the page title is disappeared.
in these cases you can change the page title by using these tags. Add the follwing content place holder in the top of your code if not exist.
<asp:Content ContentPlaceHolderId=”PlaceHolderPageTitle” runat=”server”>
Add Title here
</asp:Content>
You can get title dynamic by add any of this tags into “PlaceHolderPageTitle”
<SharePoint:ListProperty Property=”Title” runat=”server”/>
<SharePoint:ListItemProperty Property=”Title” runat=”server”/>
<SharePoint:ProjectProperty Property=”Title” runat=”server”/>
<SharePoint:ListFormPageTitle runat=”server”/>
I found this solution here.
