(Also a newb, recently promoted from noob) I’m using the starter content and this is how I got sprint to work thanks to this thread. I too was unable to return to normal walk speed before googling to this thread.
The main difference is my blueprint adds calls to the animations in the starter kit.
My first guess being unable to exit sprint is you are not re-setting the character walk speed back to the original speed. Check your float/integer variables to see if they have a defined number. Double check the links between nodes that they are not repeating or looping on eachother
The InputAction Sprint event is created by making the Input in the Project Settings under the Input Tab. You’ll need to create a new Input called Sprint and define the keybind for it. Open your character blueprint and add the InputAction Sprint. Drag from the event and search Max Walk Speed under the category Character Movement. You’ll get what my screencap shows as “Set Max Walk Speed + Target = Character Movement”. Create a new variable float/integer and call it Sprint Speed. Do the same but on the Released and create a new variable float/integer and call it Walk Speed. Compile and set Walk speed to the default (600.0) and set Sprint Speed to whatever speed you want while sprinting.