Login Problems After Upgrading to 3.5.1

Since upgrading to version 3.5.1 the form-field titles/captions on my website login page seem to have vanished, ie., there are just 2 empty boxes without the titles ‘Username’ and ‘Password’.
And the submit button is also just a blank button.
The shape of the button also seems to have changed slightly.

Also, normally when you’ve logged out it says ” You have successfully logged out….” or something like that.
This sentence too has vanished.
There is just a blank box with no words.

I’m just concerned that users may not know where to type in their name and passwords since the fields have no captions.
Checked with my hosting –everything’s OK.
My Theme is also fine and I have not changed or added any plugins.

The only thing I did was upgrade to 3.5.1 from my site dashboard.

Any help is greatly appreciated. Thanks