Error occurred during initialization of VM

So a weird thing happened to my Minecraft. And it's not starting up anymore. Firstly, I tried uninstalling my Java and reinstalled it back, I have now fixed the problem of starting up, but now its saying:

Error occurred during initialization of VM
Could not reserve enough space for 2097152KB object heap
Java HotSpot(TM) Client VM warning: Using incremental CMS is deprecated and will likely be removed in a future release

How do I fix this? 😞
And I also got this:

java.io.FileNotFoundException: File 'F:\Users\Tan\AppData\Roaming\.minecraft\assets\indexes\legacy.json' does not exist
	at org.apache.commons.io.FileUtils.openInputStream(FileUtils.java:299)
	at org.apache.commons.io.FileUtils.readFileToString(FileUtils.java:1711)
	at net.minecraft.launcher.Launcher.aE(Unknown Source)
	at net.minecraft.launcher.Launcher.aK(Unknown Source)
	at net.minecraft.launcher.game.a.B(Unknown Source)
	at com.mojang.launcher.b.b.a.b(Unknown Source)
	at com.mojang.launcher.updater.download.DownloadJob.popAndDownload(Unknown Source)
	at com.mojang.launcher.updater.download.DownloadJob.access$0(Unknown Source)
	at com.mojang.launcher.updater.download.DownloadJob$1.run(Unknown Source)
	at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
	at java.util.concurrent.FutureTask.run(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)

And now its this:

java.io.FileNotFoundException: File 'F:\Users\Tan\AppData\Roaming\.minecraft\assets\indexes\1.8.json' does not exist
	at org.apache.commons.io.FileUtils.openInputStream(FileUtils.java:299)
	at org.apache.commons.io.FileUtils.readFileToString(FileUtils.java:1711)
	at net.minecraft.launcher.Launcher.aE(Unknown Source)
	at net.minecraft.launcher.Launcher.aK(Unknown Source)
	at net.minecraft.launcher.game.a.B(Unknown Source)
	at com.mojang.launcher.b.b.a.b(Unknown Source)
	at com.mojang.launcher.updater.download.DownloadJob.popAndDownload(Unknown Source)
	at com.mojang.launcher.updater.download.DownloadJob.access$0(Unknown Source)
	at com.mojang.launcher.updater.download.DownloadJob$1.run(Unknown Source)
	at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
	at java.util.concurrent.FutureTask.run(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)

[03:06:08 SEVERE]: Game ended with bad state (exit code 1)