Nav bar disappears :(


Hello fellas!!!
I have an issue with my nav bar.
issue: for example i have two pages. a homepage having sign In button and a sign in page. i have a back button on sign in page to go back to homepage. first time i press the back button, it works. but when i press Sign in button again from the homepage, sign in page opens but without nav bar.
Home page:

click on I have an account i.e. sign in, original sign in page display first time:

i go back using back button on nav bar and again click on i have an account from homepage and this is what it displays second time:

i am running app using ionic serve on desktop cmd
No nav bar. Please help me.
Thanks in advance