So when things not working as it should, you may try out with resetting your widget templates to default. Resetting widget templates will remove changes made directly to your template via Template Editor and may affect to stylesheet changes. But it doesn't remove your widgets and data related to widgets. So if you have deleted any HTML code accidently, you will find this as a worthy solution. But if you have put a lot of customization into your template, you gotta try this as your final solution as you may never wanna lose your previous customizations. But it depends on your requirements and its priority.
1. Go to Blogger Dashboard.
2. Click on your Blog Title.
3. Navigate to Template tab.
Note: Before editing your template, you may want to save a copy of it. Read How to Back Up Your Template.
4. Click Edit HTML button underneath your blog preview.
5. Now click on Revert widget templates to default button.
6. Then you will get a prompt asking which widgets you need to revert back to default. If you know what widget you need to revert back, select it or else, you can select all to revert all widgets.
7. Now click Revert selected widgets button to continue.
8. Save your template.