How can I resurrect my Windows Store app after several packages fail to load?

The last time I had my Windows Store app open (last night), I had a XAML error in it. I (tried to) open it tonight to try to fix it, but got all kinds of errors about things not being able to be loaded. Here are the important excerpts from the ActivityLog.xml file:

460 2014/12/25 01:39:17.198 Error VisualStudio SetSite failed for package [LocalHistoryPackage] {3A6E8827-8C64-42EC-B83A-9CA32DA7BBF5}

---

80131500 No exports were found that match the constraint: ContractName Microsoft.VisualStudio.Text.ITextDocumentFactoryService RequiredTypeIdentity Microsoft.VisualStudio.Text.ITextDocumentFactoryService

. . .

935 2014/12/25 01:43:39.091 Error VisualStudio SetSite failed for package [LocalHistoryPackage] {3A6E8827-8C64-42EC-B83A-9CA32DA7BBF5}

---

80131500 No exports were found that match the constraint: ContractName

Microsoft.VisualStudio.Text.ITextDocumentFactoryService RequiredTypeIdentity

Microsoft.VisualStudio.Text.ITextDocumentFactoryService

. . .

937 2014/12/25 01:43:39.092 Warning VisualStudio Package failed to load; error message suppressed by skip flag {3A6E8827-8C64-42EC-B83A-9CA32DA7BBF5}

. . .

966 2014/12/25 01:43:52.147 Error VisualStudio SetSite failed for package [Microsoft.VisualStudio.Editor.Implementation.EditorPackage] {E269B994-EF71-4CE0-8BCD-581C217372E8}

---

80131500 No exports were found that match the constraint: ContractName

Microsoft.VisualStudio.Utilities.IContentTypeRegistryService RequiredTypeIdentity

Microsoft.VisualStudio.Utilities.IContentTypeRegistryService

I shut VS down, reopened it and the project and, although I didn't see all those err msgs, and the project was ostensibly open, there was nothing in the Solution Explorer (no files displayed). I tried opening MainPage via File > Open, but that just resulted in another err msg.

The only other thing that changed the last time I had the project open was that I updated SQLite from version 3.8.7.1 to 3.8.7.2

What could be the solution (no pun intended)?