Laravel:How to redirect back to form with input for Success message

<input type="text" name="username" value="{{ old('username') }}">

protected function submitregisteration(Request $request)
    {
        $data = $request->all();
        log::info('yeh data hai submitregisteration');
        log::info($data);
        $slug=$data['name'];
        $login= User::where('email',$request->email)->first();
    // =============================================================
       $phone=$request->phone;
       log::info($data);
       log::info("data"     );
       $phonedata= User::where('phone', $phone)->first();
       log::info("phonedata");
       log::info($phonedata);
    //    log::info($phones);
       if(!empty($phonedata))
       {
        log::info("non empty ke andar aaya");
           $phones=$phonedata->phone;
           log::info("phones");
    if($phone==$phones){
      if($request->password!=$request->confirm_password){
            return redirect()->back()->with('success', 'confirm password and password do not match.');
           }
           else {
            log::info("else if non empty ke andar aaya");
            //    return redirect()->back()->with('suc',' phone No number already exist.');
               $phone_mesg = ('phone Number already exist.');
               return redirect()->back()->with('success', $phone_mesg);
           }
    }
    //    ==============================================================
    }else
    // if($phone!=$phones)
    {
        if($request->password!=$request->confirm_password){
            return redirect()->back()->with('success', 'confirm password and password do not match.');
           }
           if($login){
            return redirect()->back()->with('message', 'email already exist,please login.');
           }
           else{
            $mfilter = str_replace("","%",$slug);
            $user = User::create([
                'name'      => $data['name'],
                'slug'      =>  $mfilter,
                'email'     => $data['email'],
                'phone'     => $data['phone'],
                'confirm_password'     => Hash::make( $data['confirm_password']),
                'password'  => Hash::make($data['password']),
                'role_id'  => 3,
            ]);
            $this->guard()->login($user);
            if ($response = $this->registered($request, $user)) {
                return $response;
            }
            return $request->wantsJson()
                        ? new JsonResponse([], 201)
                        : redirect($this->redirectPath());
           }
     }
    }

@if(session()->get('message'))
                                    <span class="invalid-feedback" style="font-size:14px;" role="alert">
                                    {{ session()->get('message') }}
                                </span>
                                    @endif
                                    @if(session()->get('success'))
                                    <span class="invalid-feedback" style="font-size:14px;" role="alert">
                                    {{ session()->get('success') }}
                                </span>
                                    @endif
                                    @if(session()->get('msg'))
                                    <span class="invalid-feedback" style="font-size:14px;" role="alert">
                                    <{{ session()->get('msg') }}
                                </span>
                                @endif