actually.. the banners module is part of the core, and not a seperate project. It's not very easy to reinstall the module (although you could do it manually).
I didn't test, but this sql should fix the install (provided that you didnt delete the files):
SET IDENTITY_INSERT {databaseOwner}[{objectQualifier}DesktopModules] ON
INSERT INTO {databaseOwner}[{objectQualifier}DesktopModules] ([DesktopModuleID], [FriendlyName], [Description], [Version], [IsPremium], [IsAdmin], [BusinessControllerClass], [FolderName], [ModuleName], [SupportedFeatures], [CompatibleVersions]) VALUES (15, N'Banners', N'Banner advertising is managed through the Vendors module in the Admin tab. You can select the number of banners to display as well as the banner type.', N'01.00.00', 0, 0, NULL, N'Banners', N'Banners', 0, NULL)
SET IDENTITY_INSERT {databaseOwner}[{objectQualifier}DesktopModules] OFF
SET IDENTITY_INSERT {databaseOwner}[{objectQualifier}ModuleControls] ON
INSERT INTO {databaseOwner}[{objectQualifier}ModuleControls] ([ModuleControlID], [ModuleDefID], [ControlKey], [ControlTitle], [ControlSrc], [IconFile], [ControlType], [ViewOrder], [HelpUrl]) VALUES (28, 20, NULL, NULL, N'Admin/Vendors/DisplayBanners.ascx', NULL, 0, NULL, NULL)
SET IDENTITY_INSERT {databaseOwner}[{objectQualifier}ModuleControls] OFF
INSERT INTO {databaseOwner}[{objectQualifier}ModuleControls] ([ModuleControlID], [ModuleDefID], [ControlKey], [ControlTitle], [ControlSrc], [IconFile], [ControlType], [ViewOrder], [HelpUrl]) VALUES (29, 20, N'Edit', N'Edit Banners', N'Admin/Vendors/BannerOptions.ascx', NULL, 1, NULL, NULL)
SET IDENTITY_INSERT {databaseOwner}[{objectQualifier}ModuleDefinitions] ON
INSERT INTO {databaseOwner}[{objectQualifier}ModuleDefinitions] ([ModuleDefID], [FriendlyName], [DesktopModuleID], [DefaultCacheTime]) VALUES (20, N'Banners', 15, 0)
SET IDENTITY_INSERT {databaseOwner}[{objectQualifier}ModuleDefinitions] OFF
You can run this SQL from host>sql.
If you did delete the files during uninstall, compare the files in your /admin/vendors directory with the /admin/vendors directory of a freshly downloaded DNN (of the same version). Make sure you have the same files in your dnn install